Stripping of membranes in buffer containing 0.4 M NaCl yielded slightly better results. Hybond membranes were reused for 5-10 times after stripping

Radiolabeled-bound probes were stripped from the membrane by boiling in 1% SDS containing 0.1X SSC for 15 min. Alternatively, membraneswereincubatedtwicein stripping solution (0.4 M NaOH)at 45°C for 30 minto remove the bound probes

Stripping of probes from hybridized membranes

After 2-3 h exposure,phosphorimagerscreenwas scannedon Fuji FLA-9000 to acquire hybridization images. Next,signal intensity for each spot on the membrane for both input and outputsampleswas quantifiedusing Fuji Multi Gauge V3.0 software andpercentage intensity foreach spot relative tothe whole signal intensity ofthe membranewas determined.To identify mutants with altered survival profiles,ratio of output (Op) to input (Ip) signal for each spot (oligonucleotide tag)present on the membranewas calculated.Mutantsdisplaying at least 6-fold higher and 10-fold lower survival were selectedas “up’ (Op/Ip= 6.0) and ‘down’ (Op/Ip = 0.1) mutants, respectively

Data analysis

After14-16 hincubation, hybridization buffer was decanted to a radioactive liquid waste container.Membraneswere washedtwice with 2X SSC (saline-sodium citrate) containing 0.1% SDS for 15 min at 55°C followed by two washes with 1X SSC containing 0.1% SDS for 15 min at room temperature. Post washes,membranes were rinsed with 1XSSC buffer at room temperature and exposed to phosphorimager screen for 2-3 h

Post-hybridization washes

Primers (OgRK 25 and OgRK 26, 200 pM ) –1 μl, eachTaq DNA polymerase –0.5 μlαP32-dCTP( specific activity-3,000 Ci/mMol)–2.5 μlWater –38.5 μlαP32-dCTPlabeled PCR productswere denatured by incubatingtubesat100°C for 5 min followed by immediatechilling on ice. After 2 h prehybridization, radiolabeleddenatured input and output probes were added to respective bottles and bottles were transferred to a hybridization oven set at 42ºC and 6 rpm

Two Hybond-N membranes,each carrying 96 immobilized DNA with unique signature sequences,were transferred to 15 cm long hybridization bottlesandlabeledas input and output. 10 mlprehybridization buffer was added to each bottle and bottles were transferred to a hybridization oven setat 42ºC and 6 rpm. To prepare input and output probes,genomic DNAsfrom input and output C. glabratacell pelletswere extracted using glass bead lysismethodandunique signature tags were PCR amplifiedwith nucleotide mix containing αP32-dCTP using primerscomplementary to the invariant region flanking each unique oligonucleotide sequence.Following is the composition of50 μlPCR cocktail used to prepare radiolabeledinput and output probes.10X PCR buffer–5 μldNTP mix (without dCTP, 2mM) –0.5 μldCTP (0.05 mM) –1 μl

Southern hybridization

E. colistrains containing plasmids with unique oligonucleotide signature sequences were inoculated in LBmedium containing ampicillin and grown overnight at 37°Cand 200 rpm. Plasmids were extracted, quantitated anddenatured in alkaline denaturing solution. Approximately, 200 ng of each plasmid DNA was transferred to theHybond-Nmembraneusing96-well Dot Blot apparatus. Membranes were neutralized in 2X SSC and denatured plasmids were cross-linked to Hybond-N membranes usingUV cross linker

Membrane preparation

E. colistrains carrying plasmids were inoculated and grown overnight at 37ºC and 200 rpm in LB-liquid medium supplemented with either 50 μg/ml ampicillinor 30 μg/ml kanamycin. Cells were harvested by centrifugation at 2,500g for 5 min. Plasmids were extracted using Qiagen plasmid miniprep kit following the manufacturer’s instructions. Concentration of the extracted plasmid DNAs was measured using spectrophotometerat 280 nmandstored at -20ºC

Plasmid DNA purification

Molecular biology methods

at 30°C andimages were captured after 2-8daysof incubationdepending upon the medium used

Yeast strains were grown in YPD medium for 14-16 hat 30°Cunder continuous shaking at 200 rpm. Cells were harvested from 1 mlculture, washed with PBS and were diluted to an OD600of 1. Five ten-fold serial dilutions were preparedfrom aninitial culture of 1OD600.4 μl cultureof each dilution was spotted onYNB-agar plates containing different carbon sources. For spotting on YPD plates containing different compounds, 3 μl cultureof each dilution was spotted. Plates were incubated

Serial dilution spotting assay

weretransferred toa sterile 100 mm cell culture dishcontaining 11 mlfresh and prewarmed completemedium andculturedin tissue culture incubatorat37°C and 5% CO2.After 12hincubation, medium was replacedwith fresh prewarmed mediumand cells were allowed to proliferate till they acquire 80% confluence

Freezer stocks of THP-1 and Lec-2 cells were prepared either in commercial cell preservation medium (Gibco) or completemedium supplemented with 10%heat inactivated serum and 10% DMSO. For cryopreservation, 5-6 million cells were resuspended in 0.5 mlfreezing medium in 2 ml cryopreservation vials,stored in an isopropanol bath and were transferred to-70°C freezer. Aftertwo days, freezer stocks were transferred to liquid nitrogen containertill further use. To revive the cells, freezer stocks were taken outfrom liquid nitrogen container and transferred immediately to37°C water bath. After2-3 min, when freezing medium hadthawed completely,cells

Cryopreservationand revival of cell lines

SDS-loading buffer was prepared as a 4X stock solutionin H2Oand used at a 1X concentration.SDS-PAGE running buffer0.25 M Tris-HCl (pH 8.0)1.92 M Glycine1% SDSRunning buffer was preparedas a 10X stock solution and diluted to 1X concentration before use.Buffers for Western blotanalysisTransfer buffer (10X stock solution)0.25 M Tris-HCl (pH 8.0)1.92 M Glycine1% SDSTransfer buffer was prepared as a 10X stock solution and diluted to 1X concentration.1X Transfer buffer (1 litre)200 ml of methanol100 ml of 10X transfer buffer700 ml of waterTris-BufferSaline (TBS)25 mM Tris150 mM NaClpH was adjusted to 7.4 with HCl.TBS buffer was prepared asa10X stock solution and diluted to 1X concentration.Blocking and wash buffers (PBS-T and TBS-T)5% Fat-free milk0.1% Tween-20Volume was made to 100 ml with 1X TBS

1 mM sodium orthovanadate1 X protease inhibitor cocktail SDS-PAGE30% Acrylamide solution29 g Acrylamide1 gBis-acrylamideDissolved in 100 ml H2O.10% Sodium Dodecyl Sulfate (SDS)10 g SDS in 100 ml H2OResolving gel mix (12%) (20 ml)6.6 ml H2O8 ml 30% acrylamide:bisacrylamide (29:1) mix5 ml 1.5 M Tris-HCl (pH 8.8)200 μl 10% SDS200 μl 10% Ammonium persulfate(APS)8 μl N,N,N′,N′-Tetramethylethylenediamine(TEMED)Stacking gel mix (5%, 6 ml)4.1 ml H2O1 ml 30% acrylamide:bisacrylamide (29:1) mix750 μl 1 M Tris-HCl (pH 6.8)60 μl 10% SDS60 μl 10% APS6 μl TEMEDSDS loading buffer130 mM Tris-HCl (pH 8.0)20% (v/v) Glycerol4.6% (w/v) SDS0.02% Bromophenol Blue2% DTT

Whole cell lysis buffer (Homogenizing buffer)50 mM Tris-HCl (pH 7.5)2 mM EDTA10 mM sodium fluoride

Buffers for protein extraction and analysis by SDS-PAGE (sodium dodecyl sulphate-polyacrylamide gel electrophoresis)

Oligonucleotides used in this study were designed either by freely available online tool Primer 3 plus (http://www.bioinformatics.nl/cgi-bin/primer3plus/primer3plus.cgi/)or Generunner software. Oligonucleotides were commercially synthesised at MWG Biotech Pvt. Ltd., Bangalore, India. Oligonucleotides used in this study are listed in Table 2.3

Oligonucleotides

competent cells pre-inoculum was prepared. A single bacterial colony was picked from LB agar plate that has been incubated for 16-20 hours at 37 °C and inoculated into 3 mlLB medium and incubated overnight at 37 °C temperature with 200 rpm shaking. 1% of this pre-inoculum was sub cultured in 100 ml LB-broth and incubated at 18 °C until OD 600 reached 0.5 -0.6 (approx.). Culture was kept on ice for 10 min. with constant shaking. Cells were pelleted by centrifugation at 2000xg/4°C/8 min. Pellet was resuspended in 40 ml of ice-cold Innoue buffer. Bacterial suspension was kept on ice for 30 min, re-spun at 2000 xg/4°C/8 min. Pellet was resuspended in 8 ml of TB buffer inwhich final concentration of DMSO was 7% and left on ice for 10 min. 100μl aliquots were made and snap frozenin liquid nitrogen and stored at -80 °C

All the salts (10 mM PIPES, 15 mM CaCl2.2H2O, 250 mM KCl,55 mM MnCl2. 2H2O) except MnCl2were dissolved in water and pH was adjusted to 6.7 with 1N KOH. MnCl2was dissolved separately in water. MnCl2was added drop wise while stirring (MnCl2if added directly will give a brown colour to the solution and precipitates;hence it needs to be dissolved separately). Solution was then sterilized by filteringand stored. To prepare

PreparationofUltra competent cells

Of theligation mixture,2μl (of total volume of 10 μl reaction)was added to atube of 100μlultra competent DH5α bacterial cells and incubated in ice for 30 minutes. The tubewas quickly transferred to a water bath maintained at 42°C to give a heat shock for 90 seconds and again quickly transferred to ice. 1ml of LB broth was added to the tube and then incubated at 37°C for 1 hour. The bacterial cells were then pelletdownby centrifugation at 6000 rpm for 5 minutes and plated on LB agarcontaining appropriate antibiotic

Transformation of ligated DNA

A total of 100-200ng of DNA was used in each ligation reaction. Vector to insert ratio of 1:3 to 1:5was maintained. The reaction volume was generally maintained at 10μl containing 1μl of 10X ligation buffer (provided by the manufacturer) and 0.05 Weissunit of T4-DNA ligase. The reaction was carried outat 16ºC for 14-to 16-hrs or at room temperature for 4hours

Ligation of DNA

Digested DNA fragments required for ligation were eluted from the agarose gel after electrophoresis. The gel was visualised over a UV illuminator and section of it containing the desired DNA fragment was carefully sliced out from the gel. The sliced agarose gel was then processed using commercially available gel elution kitsfor this purpose. The elution efficiency was checked by running a small aliquot of DNA sample on agarose gel

Purification of DNA by gel elution

For restriction digestion(either single or double), 0.5 to 1μg of DNA was used in a reaction containing2 to 5units of commercially available restriction enzyme(s)and 5μl of the recommended buffer (suppliedas 10X concentrationsby the vendor)in atotal reaction volume of 50μl. The reaction mixture was incubated for 2 h or overnight at 37°C. The digested DNA fragments were then visualised by ethidium bromide staining after electrophoresis on agarose gels. Commercially available DNA size markers were loaded along with the samples to ascertain or estimate the sizes of the digestedfragments

Restriction enzyme digestion

Overnight grown bacterial culture (3ml)was pellet down by centrifugationat4ºC for10-min at 6000 rpm. The cells were re-suspended in 200μl of Resuspension solution(solutionI). 400μl of freshly prepared Lysissolution(solution II)was then added and mixed by gently inverting the tubesfor 4-6 times and allowed to lyse for 5 min at room temperature.The complete lysis was ascertained by uniformity and clarityof the contents. Subsequently, 400μl of Neutralization solution(solution III)was added and the tubes were inverted 4-6 timesand gently for homogeneous mixing followed byincubation for 5 min on ice. After centrifuging at 12,000 rpm for 15-min, supernatant was decanted into a fresh tube, and0.7 volume of iso-propanol was added.Theprecipitated nucleic acids were then recovered by centrifugation at 12,000 rpm for 30-min. The pellet was washed once with 70% ethanol, air-dried and re-suspended in 100μl of TE-buffer. It was treated with RNase at a concentration of 20μg/ml by incubating at 37ºC for 1hour. It was further extracted with an equal volume of phenol: chloroform: isoamyl alcohol (25:24:1) mixture. After centrifugation, the clear supernatant was used for recovering the nucleic acids. The nucleic acids were precipitated with 2.5 volumesof ethanolin presence of3 M sodium acetate. In case where high purity plasmid preparations are required (for transfection to cells) the plasmid isolation was carried out with the commercially available midiprep or miniprep kits following the manufacturer’s instruction. Plasmids were observed on 1% agarose gel

Isolation of plasmid DNA

Recombinant DNA techniques

2μg of total RNA was reverse-transcribed using SuperScript III Reverse Transcriptase which is a commercially available version of M-MLVRT with reduced RNase H activity and increased thermal stability.According to manufacturer’s protocol1μg of RNA,1μl oligo(dT)(500ng),1μl 10mM dNTPand nuclease freewater was added to afinal volume of 13μlin a PCR tube.Thismixture was then incubated at 65°C for 5 minutesin a thermo cyclerand then quicklytransferredtoicefor 1minute. To this 4μl of 5X first strand buffer 1μl of 0.1MDTTand1μl ofRNaseOUT (40U/μl) were added. Then contents were then mixed and 1μl (200 units/μl) of SuperScript III RT was added. Themixture was then incubated at 50°C for 60 minutesin a thermo cycler.Lastlythe reaction was stopped byincubating the mixture at 70°C for 15 minutes. The cDNA thus prepared was then usedas a template for PCR

RT-PCR (Reverse Transcriptase PCR)

drop wiseaddition and kept at 4⁰C for 24h. Cells were then washed with PBS and stained with DNA staining solutionat 370C in darkwith intermittent shaking. The DNA content of cells was measured by flow cytometryusing FACS-Aria (Beckton-Dickenson) at 695 ±20 nm using a 655 long pass filter.The DNA content was then analysed by FACSDivaor FlowJosoftwareto evaluate the various phases of cell cycle. The diploid 2N DNA content was referred as G1/G0 population and the 4N DNA content was referred as G2/M population. Cells with intermediary DNA content (between 2N -4N) content were considered as S phasecells and those below 2N DNA content as sub G0 cells

Thecells were collected at various time points by trypsinization, washed in phosphate buffered saline (PBS, pH 7.2) and fixed in chilled 70% methanol: ethanol (1:1) solution by

Cell cycle analysis

Malachite green reagent

DNA loading dye

Neutralization solution(Solution III)

EMSA Buffer

Blocking buffer: 2% BSA

Stripping Buffer

Blocking Buffer

TBST

Transfer Buffer

Running Buffer

Stacking and resolving AcrylamidegelsResolving gel (10 ml)

6X protein loading buffer (Laemmlibuffer)

Cell lysis buffer(RIPA Buffer)

For Immunoblotting

Sodium Chloride (NaCl)ComponentsFinal concentrationFor 100 mlNaCl5M29.22gH2Oq.s

Briefly, cells were cultured on 35 mm culture dishes (Corning) and were transfected with pcDNA3.1 (+) empty vector or pcDNA3.1 (+) profilin-1 clone (encodes for neomycin resistance for selection in mammalian cells) using Lipofectamine 2000 reagent. The following day, cells were trypsinized and plated in four 10 cm culture dishes separately for each cell clones in selective media containing 800μg/ml of Geneticin, G418 (whose concentration was obtained from kill curve based on MTT assay). Over the time,it will select only those cells that have stably incorporated the plasmid into their genomic DNA. Cells were selected in G418 for about two weeks until colonies appeared. Meanwhile, cells were regularly washed with sterile PBSto remove dead cells from culture dishes. Colonies were picked using a pipettewith a sterile tip by loweringitto the surface of the colony of interest, followed by gentle scraping and rapid sucking.About 20 colonies were picked, followed by dilution plating in 96-well plates until single cell per well was obtained to establish a pure colony. Once colonies have reached to fair confluency, they were further expanded by dilution plating and screened for stable expression of profilinby immunoblotting and semi-quantitative RT-PCR. Once the clonal cell line is established, aliquots were freezed for future use and rest were maintained in lower concentration of G418 with proper track of passage number

Generation of profilin stable MDA-MB-231 cells

5X EMSA buffer

6X DNA loading dye

Blocking buffer: 2% BSA

Permeabilisation buffer: 0.2% Triton X100

4% Formaldehyde fixative

For Immunofluorescence(IF)

(c) 6X Protein loading buffer (Lammeli buffer)

Wild type or H133S mutant of profilin-1 witheither FLAG or un-tagged werecloned in pcDNA3.1 (+).Mdm2 gene upstreampromoter region having p53 binding site was cloned in pLUC vector (designated as p53-Luc). The constructs of NF-κB-SEAP, p65 (RelA), wild type and dominant negativeIKKβ(IKKβ-WT and IKKβ-DN, respectively)were a kind gift fromProf.Bharat B. Aggarwal (M. D. Anderson Cancer Center,Houston, TX). The constitutive active mutant of IKKβ, in which two serine residues are mutated to glutamic acid, at position 177 and 181 (referred as IKKβ-EE or IKKβ-CA) was gifted byProf. GourisankarGhosh (University of California, San Diego, USA).FLAG or Myc tagged Full length andtruncationmutants of PTEN wereprovided by Dr.M.Subba Reddy (CDFD, Hyderabad).For p53 gene knockdownstudies, TP53 mission shRNA were obtained from Sigma Aldrich (St Louis, MO, USA). For PTEN silencing, retroviral vector based PTEN shRNA (shRNA#1-AGGCGCTATGTGTATTATTAT; shRNA#2-CCACAGCTAG-AACTTATCAAA; shRNA#3-CCACAAATGAAGGGATATAAA)wasgifted by Dr. M.Subba Reddy (CDFD, Hyderabad)

Plasmids

To monitor yeast cell death 1 OD600equivalent cellsfrom mid-log and overnight growncultures were pelleted, washed in PBS and the cell pellet was suspended in 100 μL of PBS. 20 μLof 0.4% trypan bluesolution was added to 20 μLof cell suspension and incubated for 10 min. 20 μL of this suspension was placed on a slide, covered with a cover slip, and cell death was measured by scoring dead cells that take up the dye.To monitor cell viability, cells equivalent to 10-5OD600 from mid-log and stationary phase cultures were plated on YPD-agar, incubated at 30°C for 48 h, and colonies were counted to extrapolate viable cell count per OD600

To determine yeast cell mass, cells equivalent to 5 OD600were harvested from mid-log and overnight growncultures, and washed twice with PBS. Cell pellets were dried at 50°C for 20 minand the dry weight of yeast was measured. To assess the cell number, cells in mid-log or stationary phase were counted using a Neubauer chamber and the number of cells present in 1 OD600was calculated

Cell mass, cell numberand viability assessment

20 mM HEPES500 mM NaCl 2 mM EDTA1% Triton-XYeast protease inhibitor cocktail and phosphatase inhibitor cocktail (added fresh to the buffer C)IP7 reaction buffer(10X)250 mM HEPES,pH 7.4500 mM NaCl60 mM MgCl210 mM DTT (1 M stock was made separately, aliquoted into 100 μL and stored at -20oC).10X buffer was made and stored at 4oC. An appropriate amount was added to the reaction mix to get a final concentration of 1X.DTT was added fresh to the reaction buffer just before use

Buffer C

50 mM Tris-HCl,pH7.450 mM NH4Cl12 mM MgCl21 mM DTT0.1%DEPC37% sucrose solution

100mM NaCl30mM MgCl250μg/mLcycloheximide 200μg/mL heparin All the components were made in DEPC treated water.Gradient buffer10% sucrose gradient buffer50 mM Tris-HCl,pH7.450 mM NH4Cl12 mM MgCl21 mM DTT0.1%DEPC10% sucrose solutionTo analyse individual ribosome subunits, MgCl2 was eliminated from the gradient buffer.30% sucrose gradient buffer50 mM Tris-HCl,pH7.450 mM NH4Cl12 mM MgCl21 mM DTT0.1%DEPC30% sucrose To analyse individual ribosome subunits, MgCl2 was eliminated from the gradient buffer.50% sucrose gradient buffer50 mM Tris-HCl,pH7.450 mM NH4Cl12 mM MgCl21 mM DTT0.1%DEPC50% sucrose To analyse individual ribosome subunits, MgCl2 was eliminated from the gradient buffer.37% sucrose gradient buffer

Lysis buffer10mM Tris, pH7.4

Buffers for ribosome and polysome analysis

Oligonucleotides used in this study were designed manually by examining the relevant DNA sequences. Oligonucleotides were commercially synthesised at MWG Biotech Pvt. Ltd., Bangalore, Indiaor Ocimum biosolutions, Hyderabad, India. Oligonucleotides used inthis study are listed in Table 2.4 and 2.5

Oligonucleotides

StrainsThe

PCR product was incubated with 1ul of Dpnl restriction enzyme for 2-3 hours at 37ºC, following which Dpn1 treated PCR product was transformed into DH5α competent bacterialcells. Mutant colonies were screened andconfirmed using DNA sequencing

PCR product was incubated with 1ul of Dpnl restriction enzyme for 2-3 hours at 37ºC, following which Dpn1 treated PCR product was transformed into DH5α competent bacterialcells. Mutant colonies were screened andconfirmed using DNA sequencing

The various mutant plasmids were generatedbyusing PCR-based site-directed mutagenesis protocol (Stratagene).Briefly, primers carrying the desired nucleotide changes were used in a PCR reaction to amplify the nascent mutantplasmids from the wild type parent plasmid. The PCR reaction was set up according to manufacturer’s protocol(Table 5)using a high-fidelity Pfu DNApolymerase and donor-plasmids of the desired geneas the template. Following reactionmixture and the cycling conditions were used for site-directed mutagenesis

Site-directed mutagenesis

All the primers (sequences)used for cloning the above-mentioned genes are providedin AppendixI

using gateway cloning method (Invitrogen). P73domain deletions were cloned in SFB destination vector. WWP2, WWP1, HACE1, E6AP, and PPM1G were cloned into SFB (S-protein/Flag/streptavidin binding protein (SBP) triple tag), GFP,and Myc mammalian destination vectors using the Gateway cloning technology (Invitrogen). WWP2 domain deletions were cloned into Myc-destination vector. WWP1 domain deletions were cloned into SFB-destination vector. PPM1G domain deletions were cloned into SFB mammalian destination vector using Gateway cloning. Bacterially expressing GST-p73, GST-∆Np73, GST-PPM1G, MBP-WWP1, MBP-WWP2, GST-WWP2, GST-WWP1 and GST-HACE1 were generated by using gateway technology. Ubiquitin WT and all the mutants were cloned into hemagglutinin (HA) mammalian destination vector. Flag-tagged Dvl2was purchased from Addgene. Dvl2 domain deletions were cloned into SFB-destination vectors. All the plasmid constructs generated in the present study are mentioned in table 2.Table 2: Plasmids used in the study

TAp73α and ∆Np73α were kindly gifted by Alex Zaika, Vanderbilt University. Full-length p73 and ∆Np73 were cloned into Myc and HA mammalian destination vectors

Expression plasmids

Four week old tomato S-22 cultivar (acts as non-host for Xanthomonas oryzae pv. oryzicola) were syringe-infiltrated with a suspension of Xocstrains and water control. Plants were incubated in green house for 24 h with minimum and maxium temperature of 26 and 28°C, respectively and relative humidity of 65%. Callose deposition assay was performed as a marker for hypersensitvity response in non host plant as described previously (Hauck et al., 2003). Leaf picture was captured at this stage to observe the HR browning of leaf. For assaying callose deposition by aniline blue staining, infilterated leaves were removed from plant,dipped in lactophenol solution and incubated at 65°C in water bath until the cholorohyll is completely removed. Leaves were rehydrated by washing with 50% ethanol, and finally rinsed with water. For aniline blue staining, leaves were incubated in 0.01% aniline blue solution, prepared in 100 mM K2HPO4(pH 9.5), for 15-20 min in dark. Subsequently, leaves were washed with water and observed for callose deposition in epifluorescence microscope (Stereo, Lumar V7, Zeiss) under UV illumination

In plantahypersensitive response (HR) and callose deposition assay

flash (Thermoscientific). β-Glucuronidase activity for GUS was expressed as nanomoles of MU produced/minute/108 cells

In planta siderophore gene expression was studied by measuring β-glucuronidase activity. GUS marked BXOR1 strain and wild-typeBXOR1 (control) were inoculated in the leaves of 14 day old susceptible Taichung Native 1 (TN-1) variety of rice. After 10 days of inoculation, leaves were crushed and dissolved in 1 ml of MUG extraction buffer without adding MUG substrate (4-methylumbelliferyl β-D-glucuronide). Subsequently, 250 μl extraction buffer containing MUG was added, and incubated at 37°C for appropriate time (Jefferson et al., 1987). Next, 75-μl aliquots were taken from each reaction mixture, and the reaction was terminated by the addition of 675 μl Na2CO3 (0.2 M). Fluorescence was measured against 4-methyl-umbelliferone (MU; Sigma) as standard at excitation/emission wavelength of 365/455 nm, respectively in

In plantaGUS expression assay for siderophore cluster

grown culture was inoculated in fresh PS medium with or without 50 μM 2, 2’-dipyridyl and grown at 28°C. At regulartime intervals, 1 ml culture was removed to determine OD at 600 nm. Furthermore, for GUS assay, 1 ml culture was centrifuged to obtain the pellet, which was washed once in sterile miliQ water, and resuspended in 250 μl volume of 1 mM MUG (4-methylumbelliferyl β-D-glucuronide) extraction buffer (50 mM sodium dihydrogen phosphate [pH 7.0], 10 mM EDTA, 0.1% Triton X-100, 0.1% sodium lauryl sarcosine, and 10 mM β-mercaptoethanol),and incubated at 37°C (Jefferson et al., 1987). After appropriate time intervals, 75 μl aliquotes were taken from each reaction mixture, and reaction was terminated by adding 675 μl Na2CO3 (0.2 M). Fluorescence was measured against 4-methyl-umbelliferone as the standard at excitation/emission wavelength of 365/455 nm, respectively. Likewise, GFP activity was measured in Varioscan flash (Thermoscientific) at exitation/emission wavelength of 472/512 nm, respectively by taking 200 μl of culture directly

For reporter assay, GUS and GFP marked Xanthomonas oryzaepv. oryzicolastrains and control strains were grown overnight in PS medium. 0.2

Reporter assays with β-Glucuronidase (GUS) and green fluorescent protein (GFP)

2 bed volumes of methanol, and equilibrated with 5 bed volumes of distilled water. In order to reduce the water solubility of siderophore in the supernatant, it was acidified to pH 2 using concentarted HCl. This acidified supernatant was passsed through the column, and finally eluted with 160 ml methanol by collecting approximately 60 fractions (2 ml each) of the flow through. Siderophore assay was done on CAS plate with each collected fraction. Fraction that gave orangish-yellow halo for the siderophore on CAS plate, was combined together, dried in rotary evaporator and finally reconstituted in 1 ml methanol for further quantification using HPLC as described previously (Amin et al., 2009).For HPLC analysis, siderophore samples were filtered through filter membrane (porosity, 0.45 μ). Next, 10 μl sample was injected into Agilent C18 (4.6mm×250mm×5μm) column (gradient:(A=H2O/0.1%TFA), (B= CH3CN/0.1%TFA) 0-30% B in 10 min, 30-45% B in 15 min,45-0%B in 20 min at a flow rate of 1 ml/min). Similarly, standard vibrioferrin (siderophore produced by Xanthomonas) was also estimated through HPLC for comparison. Fe(III) bound vibrioferrin complex was prepared by incubating FeCl3.6H2O and apo-vibrioferrin for overnight. This complex was detected at300 nm (RT 10.998 min), whereas apo-vibrioferrin was detected at 220 nm at RT 10.988 min. The siderophore concentration in the samples were determined by peak area and calculated against the standard curves obtained from standard vibrioferrin. The siderophore from the test samples were detected at 300 nm, which confirms that majority of the vibrioferrin isolated from the culture was present in bound form

Different Xanthomonas oryzaepv. oryzicola strains were grown overnight in PS medium at 28 °C and 200 rpm. 0.2% of the overnight grown culture was inoculated in the the fresh PS medium supplemented with 50 μM 2, 2’-dipyridyl, and grown till OD600 reached to 1. Cultures were centrifuged at 12,000 g for 50 min to get the cell free culture supernantant, which was collected into acid treated bottles. Excess exoplysaccharide was removed by centrifugation for longer time. Siderophore was initially isolated by column chromatography as described previously (Wright, 2010). Briefly, 220 g of XAD-16 resin was soaked overnight and packed into the column (2.4×30 cm), column was wa

HPLC based siderophore estimation from culture supernatant of different strains of X. oryzaepv. oryzicola

concentarion in the samples were determined based on their peak area against standard oxalic acid plot.For GC-MS analysis, N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) derivatization was performed with the dried HPLC fraction of samples as well as standards as described previously (Šťávová et al., 2011). Briefly, 200 μl BSTFA, and 100 μl hexane were added to the sample, and incubated at 50 °C for 70 min. GC analyses were performed using a Shimazdu GP 2010 plus instrument equipped with an autosampler, and a split injector.Separations were accomplished using a 30-m long DB-5 capillary column, 0.25 mm internal diameter (I.D.) at a constant helium flow rate of 1.5 mL/min. Samples (10 μL) were injected with a split ratio of 10 into the column at 100 °C. The final column temperature program started at 100 °C and attained final temperature 280°C with a gradient increase of 5 °C/min. The MS data (total ion chromatogram,TIC) was acquired in the full scan mode (m/z of 50–500) at a scan rate of 1000 amu using the electron ionization (EI) with an electron energy of 70 eV. The acquired spectrum was searched against standard NIST-05 library

Xanthomonas oryzaepv. oryzicola strains were grown overnight in PS medium supplemented with appropriate antibiotics. 0.2 % of the overnight grown culture was reinoculated in 250 ml of fresh PS medium supplemented with 50 μM 2,2’-dipyridyl, and allowed to grow till OD600reached 1. Cultures were centrifuged to obtain cell free culture supernatant, concentrated on vaccum evaporator, and freeze dried at regular time intervals to remove the water completely. Oxalic acid was estimated from the dried supernatant by using Agilent 1100 series HPLC system as described previously with slight modifications (Ding et al., 2006). In brief, dried supernatant fractions of different cultures were dissolved in mobile phase of pH 2.7, and allowed to stand for 3 h for the precipitation of humic substances. These samples were filtered through membrane filter (porosity, 0.45 μm), and 20 μl volume of the filtrate was injected into the Agilent C18 (4.6 mm× 250 mm× 5 μm) column. The mobile phase used was 10 mM KH2PO4-CH3OH (95:5, pH 2.7), and the samples were separated by isocratic elution at 0.8 mL/min at 26°C temperature. Standard oxalic acid was detected in similar way in mobile phase (pH 2.7 at 210 nm) with retention time (RT) of 6.7 min. Likewise, oxalic acid in the test samples were also detected at 210 nm with RT 6.7

Oxalic acidestimation from culture supernatant of different strains of X. oryzaepv. oryzicola by HPLC and GCMS analysis

CFUs/ml) onto fully expanded leaf, and pricking with sterile needle to facilitate the entry of bacteria inside the leaves through wound. To detrmine the growth of bacteria inside leaves, 1 cm2 leaf area surrounding the inoculation site was cut at regular time intervals, surface sterilized by dipping in 2% (vol/vol) sodium hypochlorite for 2 min, and washed twice in sterile water. For getting the CFUs, leaves were crushed using mortar and pestle, serially diluted, and plated on PSA medium containing appropriate antibiotics

Exogenous iron supplementation was performed as described previously (Chatterjee and Sonti, 2002). Briefly, leaves of 40-day-old greenhouse-grown rice plants of the susceptible rice cultivar Taichung Native-1 (TN-1) were cut with scissors 2 cm above the junction of the leaf blade and leaf sheath. These cut leaves (25 leaves per flasks) were dipped in 250 ml conical flasks containing 200 ml 1μg/mlof Benzyl amino purine (BAP) in double distilled water. BAP (a cytokine hormone) maintain the detached rice leaves in fresh condition for longer period. For iron supplementation, FeCl3 was added to a final concentration of 50 μM (stock-10 mM). Prior to inoculation with different strains of Xanthomonas oryzaepv. oryzicola, the leaves were maintained overnight on a laboartory bench top. Strains were inoculated into the leaves by needle pricking method by dropping 20μl of bacterial suspension (approx. 1 × 108bacterial

Exogenous iron supplementation and bacterial growth assay in rice leaves

Ferric-iron-reduction activity of Xanthomonas oryzaepv. oryzicolawas measured using ferrozine, a chromogenic ferrous iron chelator, as described previously (Velayudhan etal., 2000; Worst et al., 1998). For estimating the ferric reductase activity, Xanthomonas oryzaepv. oryzicolastrains were grown in 20 ml PS medium carrying appropriate antibiotics for 24 h to OD600 of 1. Cell free PS media was incubated under similarcondition to be used as control. Chromogenic ferrous iron chelator, ferrozine was added to a final concentration of 1 mM, and FeCl3was added as ferric iron source to a final concentration of 50 μM, and incubated at 28ºC. At regular time intervals, 1 ml aliquotes were taken from the test culture and control, centrifuged to remove the cells, and absorbance of the magenta coloured Fe2+-ferrozine complex in the cell free culture supernantant was measured at 535 nm by using control supernatant as reference. The Fe2+reduction activity was quantified as micromoles of Fe2+-Ferrozine complex formed

Assay for ferric reductase activity

media containing 50 μM 2’2’-dipyridyland grown for 24 h at 28°C with continuous shaking at 200 rpm. Cells were harvested by centrifugation at 7000 g for 10 min at 4 °C, washed twice with 50 mM phosphate buffer (pH-7.4), and finally resuspended in phosphate buffer. The bacterial suspension was then diluted with chelex-100 treated PS to get a final OD600of 1.0 and incubated at 28°C for 5 min. Iron transport assay was initated by adding 55FeCl3(American radiolabeled chemicals, Inc., St. Louis, USA,specific activity 10.18 mci/mg) to a final concentration of 0.4 μM into the bacterial suspension. The radiolabelled stock solution was diluted with water and 1M sodium ascorbate for 55Fe3+uptake and 55Fe2+uptake studies, respectively. For uptake of FeCl3bound vibrioferrin, both vibrioferrin (7.6 mM stock) and 55FeCl3were incubated in 1:1 ratio by diluting it appropriately with water and uptake was initiated with a final concentartion of 0.4 μM. To stop the uptake, 200 μl of bacterial cell suspension was layered and immediately centifuged (13000 g; 1 min) through 300 μl of di-butylphthalate and di-octyl phthalate (1:1) mixture. The upper aqueous layer and organic solvent was aspirated, and pellet was resuspended in 100 μl Triton-X-100. The suspension was added to 5 ml scintillation cocktail, and radioactivity count was determined in the 3H channel of scintillation counter (Perkin Elmer, Liquid Scintillation analyzer, Tri-Carb 2910 TR, USA). As control, both Fe2+and Fe3+uptake assays were performed in presence of proton motive force uncoupler carbonylcyanidep-trifluoromethoxyphenylhydrazone (FCCP; 50 μM), to distinguish between non-specific uptake of readiolabelled Fe by the bacterial cells. However, no significant increase in the incorporation of Fe2+and Fe3+ was observed in presence of FCCP, which indicated that iron uptake by these strains is energy-dependent process

In vitro transport assay was performed by using radiolabelled iron to measure the capacity of Xanthomonas oryzaepv. oryzicola strains to transport 55Fe(II) and 55Fe(III) forms of iron as described previously with slight modifications (Ardon et al., 1997; Velayudhan et al., 2000). For iron uptake asssay, Xocwild-type BXOR1 strain, ∆rpfF mutant and the complemented strain harboring full length rpfFgenewere grown overnight in PS medium. 0.2% of the overnight grown culture was inoculated in fresh P

55Fe uptake assay

Intracellular iron content in different Xanthomonas oryzaepv. oryzicolastrains was measured by using atomic absorption spectroscopy as described previously with few modifications (Velayudhan et al., 2000). For estimation of intracellular iron, different strains of Xanthomonas oryzaepv. oryzicolawere grown overnight in 3 ml PS media with appropriate antibiotics for differentially marked strains. 0.2% of the overnight grown culture was inoculated in 250 ml PS medium alone or PS plus 2, 2’-dipyridyl for iron stravation, and grown to an OD600 of 1.2. Cells were then pelleted down by centrifuging at 7000 g for 10 min, and washed twice with phosphate buffer saline (PBS). After washing, cells were lyophilized, and their dry weights were determined. Lyophilized cells were then dissolved in 30% nitric acid at 80ºC for 12 h and diluted 10-fold with miliQ water. Iron content was determined by atomicabsorption spectroscopy using ICP-OES (JY 2000 sequential Inductively Coupled Plasma Optical Emisson spectrometer,Jobin Yvon, Horiba, France). Iron level was quantified against aqueous standard of iron traceable to NIST (National institute of standards and technology, India)

Estimation of intracellular iron content

culture dishes and dishes were incubated at 28ºC. OD600 was measured after 16 and 42 h of incubation, and percentage inhibition of growth was determined with respect to the growth in the corresponding control cultures containing PS media without streptonigrin

For streptonigrin sensitivity assay, different strains of Xanthomonas oryzaepv. oryzicolawere grown overnight with appropriate antibiotics as described earlier. 0.2% of primary inoculum was added into fresh PS medium and grown for 24 h till the OD600reached 0.6. Serial dilution of bacterial cultures were performed as mentioned earlier, and 5μl diluted cultures were spotted on PSA plates containing different concentration of streptonigrin (0.05 μg/ml, 0.1 μg/ml and 0.15 μg/ml). Plates were incubated at 28ºC for 72 h and plate images were captured and analyzed for comparative growth inhibitionin different strains caused by streptonigrin. Further, streptonigrin sensitivity assay in liquid broth was performed by growing different strains as described previously (Wilson et al., 1998).Briefly, Xanthomonas oryzae pv. oryzicolastrains were grown to an OD of 1 in PS medium with appropriate antibiotics. Cells were pelleted down, and resuspended in fresh PS medium at an OD600of 0.6. Next, 100 μl culture was inoculated in 4 ml PS medium with or without streptonigrin. Streptonigrin was added to a final concentration of 0.1μg/ml into

Streptonigrin sensitivtity assay

ForEPS isolation,X. oryzaepv. oryzicolastrains were plated on PS agar plateand incubated at 28°C. Bacterial lawn was dissolved in 15 ml 1X PBS and 100 μl formamide, and centrifuged at 12,000 g for 6-8 min at RT. Before centrifugation, 1 ml cell suspension was diluted, and plated to get the CFUs. For EPS precipitation, 250 ml chilled acetone was added to the supernatant, and kept at 4°C for overnight (Dharmapuri and Sonti, 1999). EPS was pelleted down at 7000 g for 10 min at 4°C, washed with 10 ml acetone, and kept for drying. After drying, it was dissolved in appropriate volume of water, and quantitated by colorimetric method for estimation of pentoses and hexoses by phenol-sulphuric acid method (Dharmapuri and Sonti, 1999)

EPS isolation and estimation

For biofilm and attachment assays, Xanthomonas oryzaecells were grown in PS media with appropriate antibiotics at 28°C with constant shaking at 200 rpm. 0.2% of the overnight grown culture was inoculated into the fresh PS media and grown till the OD reached 0.6-0.7 at 600 nm. 4 ml culture was inoculated into 12 well polystyrene culture plates, and incubated for 24 h and 48 h at 28°C without shaking. After 24 h, cultures were discarded, and wells were washed with 4 ml of water to remove loosely attached cells. The adherence was examined by staining the cells with 1% crystal violet solution for 30 min at room temperature. After incubation, excess crystal violet stain was removed by washing the wells with 3 ml water. Images were captured for visualizing the stained biofilm on polystyrene plate. Finally, crystal violet stained biofilm was dissolved in 80% ethanol, and quantified by taking OD at 560 nm. Similar procedures were repeated for the polystyrene plate with culture incubated for 48 h. For attachment, cells were grown similarly in 12 well polystyrene culture plates for 24 h, rinsed once with sterile water to remove loosely attached cells then attached cells were collected by vigorous washing with sterile water. Attached cells were diluted, and plated to get the CFUs

Static biofilm and attachment assay

In planta growth assay for different strains of Xanthomonas oryzaepv. oryzicolawas performed by counting CFUs. For getting the CFUs, 1 cm2 leaf area surrounding the site of inoculation was cut and surface sterilized by dipping the leaf in 1% (vol/vol) sodium hypochlorite for 2 min followed by three washes with sterile water. To get the CFUs, sterilized leaves were crushed using mortar and pestle, and diluted appropriately for plating on PSA plate containing suitable antibiotics for differentially marked strains

In plantabacterial growth assay

To study the virulence of Xanthomonas oryzaepv. oryzicolastrains on rice plant two different inoculation methods, syringe infiltration and wound inoculation methods, were implimented. For infiltration method, bacterial suspension comprising of 1 × 108 cells/ml were infiltrated with needleless syringe into leaves of 4 to 6 week-old rice cultivar of susceptible Taichung Native-1 (TN-1) (Hopkins et al., 1992; Wang et al., 2007). Wound inoculation method was carried out by dropping an aliquot of 20 μl bacterial suspension comprised of 1 ×108cells/ml onto fully expanded leaf of 6-8 week green-house grown Taichung Native-1 cultivar of rice, and pricking with sterile needle for facilitating the entry of Xocinside the leaves throgh wound. For inititation of disease symptom, the inoculated plants were incubated in greenhouse with minimum and maximum temperatures of approximately 25 to 30 °C, respectively, and a relative humidity of approximately 60%. Water soaking symptom and lesion development was measured 4 to 10 days after inoculation. Likewise, for infiltration by wound inoculation method, lesion length was measured 14 days after inoculation. In both the cases, no lesions were observed in control experiments in which the leaves were inoculated with sterile wate

Virulence assay on rice plant

biosensor strain 8523/KLN55was inoculated in fresh medium, and grown with the ethyl acetate extract isolated from the test strain as described earlier. After 30 h of growth, cells were pelleted by centrifugation, washed once with sterile water and resuspended in sterile miliQ waterfor measuring the GFP fluorescence intensity at excitation and emission wavelength of 472 and 512 nm, respectively. 1 DSF unit is equivalent to increase in fluorescence by 1 arbitary unit in DSF biosensor strain

For DSF extraction, X. oryzaepv. oryzicolastrains were grown in PS media to an OD600 of 1.2 as described earlier. Supernatant was collected by pelleting down the cells at 7000 g for 10 min. Next, water-saturated ethyl acetate was added to the cell-free culture supernatant in a ratio of 2:1, and mixed properly for 5-10 min. The mixture was centrifuged at 5000 g to separate the DSF containing organic phase. The ethyl acetate layer (organic phase) was evaporated at 37°C, remaining residue was dissolved in methanol, and assayed for DSF by using Xccbiosensor strain 8523/KLN55 (Newman et al., 2004). Biosensor strain is a DSF minus strain comprised of DSF responsive endoglucanase promoter fused to promoterless gfpand expressed through plasmid (Peng::gfp). To check the DSF production by a particular strain, 0.2% inoc

Isolation and detection of DSF

For determining the motility of Xanthomonas oryzae pv.oryzae strains, swim plate assay was performed as described previously (Robleto et al., 2003; Tremaroli et al., 2010)with slight modifications. Briefly, swim plates were prepared with PSA medium containing 0.1% agar. For motility assay, cells were grown at a density of 109cells, which corresponds to an OD of 0.6. Cells were concentrated by centrifugation at 3000 g for 5 min, washed and resuspended in 1/10 volume of sterile water. 5 μl cell suspension was inoculated at the center of the swim plates and incubated for 36-48 h at 28°C. Toget the quantitative measurement of the motility of each strain, diameter of the motility zone was determined at appropriate time point

Motility assay

developer solution for appropriate time and immediately kept in fixer solution to see the protein band. For alkaline phosphatase method, blot was incubated with 5 ml of BCIP/NBT solution (Amresco) under dark condition. After incubation, blot was washed with water to see the blue-violet color protein band

volume of 50 mM acetate buffer (pH-5.4), and dialyzed overnight with 10 mM Tris buffer, pH 7.5. Pellet was used for dilution plating for calculating CFUs. For whole cell protein isolation, bacterial pellet was dissolved in 50 mM sodium acetate buffer (pH-5.4) and sonicated for 30 min (1 min on and off, Amplitude 32) by adding phenylmethylsulfonyl fluoride (PMSF) at a final concentration of 1 mM in ice-cold solution. Both extracellular proteins and whole cell lysate fractions were aliquoted in 1.5 ml microcentrifuge tube, and protein quantification was performed using a Pierce BCA protein assay kit (Thermo Scientific) as per manufacturer’s instructions using bovine serum albumin as standard and stored at -80°C for further use. Cell normalized extracellular and whole cell lysate proteins fractions from different strains were resolved on 12% SDS-PAGE gel at 90 V till the dye front reached the bottom. One gel was processed for silver staining (Sambrook et al., 1989), and other for western-blot analysis by using anti-GFP antibody. For western blot analysis, resolved proteins were transferred to Hybond-ECL membrane (Amersham biosciences) at 35 V for overnight in the cold room. Transfer of the proteins were visually confirmed by examining marker’s lane and membranes were incubated in small box for 2-3 h in 5% fat free milk prepared in 1X PBST for blocking. Blocking solutions were discarded, and primary antibody, appropriately diluted in 5% fat free milk prepared in 1X PBST, was added to the box containing membrane. After 2-3 h incubation in primary antibody, membranes were washed thrice with 1X PBST for 10 min. Membranes were incubated for 2 h in appropriate secondary antibody (anti-Rabbit antibody)diluted in 5% fat free milk prepared in 1X PBST. Blots were either developed by chemiluminescence based ECL-plus western detection system or alkaline phosphatase method. For HRP based chemiluminescence method, detection was performed using the ECL plus kit (Amersham biosciences) and incubated for 3 min. Blot was exposed to the film and developed i

For protein extraction, Xanthomonas oryzaepv. oryzaestrains with eGFP plasmid were grown for 24-30 h in PS medium to an OD of 0.8 as described above and centrifuged at 12,000 g for 10 min. The supernatant was taken as extracellular fraction and protein was extracted as described previously (Ray et al., 2000). Extracellular proteins were precipitated from this fraction by constantly adding 50% (wt/vol) ammonium sulphate at 4°C. After precipitation, the solution was kept on ice for 15-20 min and centrifuged at 12,000 g for 30 min at 4°C. The pellet was dissolved in s

Protein extraction and immunoblotting

development. Absorbance was measured at 490 nm, and concentration of glucose production was calculated against glucose standard. Cellulase activity is expressed as micromoles of reducing sugar (glucose) released per minute per 109cells. For plate assay, cell-free culture supernatant of X. oryzaepv. oryzaestrains were inoculated in wells of 0.2% CMC agarose plates. In addition, cellulase assay was also performed by spotting the colony on 0.2% CMC PSA plates. Plates were incubated for 8 to 24 h and stained with congo red to observe the halo formation as described previously (Wood and Bhat, 1988). Extracellular xylanase activity in different X. oryzaepv. oryzae strains was measured using 0.2% 4-O-methyl-D-glucurono-D-xylanremazol Brilliant Blue R (RBB-Xylan) (Sigma-Aldrich) as substrate (Biely et al., 1988)on 1% agarose plates. Xylanase activity is indicated by production of halo around the bacterial colony (Ray et al., 2000). Similarly, for lipase activity p-nitrophenyl butyrate was used as substrate. Lipase activity was calculated by measuring the level of p-nitrophenol released upon hydrolysis of p-nitrophenyl butyrate at 410 nm (Acharya and Rao, 2002). Lipase activity was expressed as micromoles of p-nitrophenol released permin per109cells. For plate assay, colonies were spotted on 1% PSA plates containing 0.5% Tributyrin in 100 mM Tris (pH 8) and 25 mM CaCl2 and halo formation was observed for lipase activity

For extracellular enzyme assays, X. oryzaepv. oryzae strains were grown in PS, MM9 and XOM2 media to an OD of 0.6, and centrifuged at 12,000 g for 10 min to collect the supernatant. The supernatant was taken as an extracellular fraction and cell pellet was plated by dilutionplating to get the CFUs per milliliter of culture. Extracellular cellulase activity was measured using phenol-sulphuric acid (H2SO4) method, which measures pentoses and hexoses (concentration of glucose released) upon cellulase activity (DuBois et al., 1956). Briefly, a specific amount of supernatant was taken and volume was adjusted to 300 μl by adding 50 mM acetate buffer (pH-5.4). To this, 1% carboxy methyl cellulose (CMC) substrate solution was added and mixed well. This mixture was incubated at 28°C for 30 min, and the reaction was stopped by adding 1 ml ice-cold ethanol. Solution was mixed well, kept on ice for 5 min and centrifuged at 12,000 g for 5 min. Supernatant was recovered and 5% phenol was added to it, mixed well followed by adding 1 ml H2SO4. The tube was incubated at RT for 20 min for co

Extracellular enzyme assays

work were autoclaved twice and dried at 80°C for overnight before use. RNA was isolated from Xanthomonasculture using Trizol method. Xanthomonascells were harvested at 12,000 g for 5 min at 4°C, resuspended in approximately 1 ml Trizol (Invitrogen),mixed properly and incubated at room temperature (RT) for 5 min. 200 μl chloroform was added to the tube, shaken for 15 seconds and incubated at RT for 2-15 seconds. Next, tubes were centrifuged at 13,000 g for 15 min at 4°C. Aqueous phase was transferred to new 1.5 ml microcentrifuge tube and RNA was precipitated by adding 500 μl isopropanol and incubated for 5-10 min at RT. Precipitated RNA was collected by centrifugation at 10,000 gfor 10 min at 4°C. RNA pellet was washed with 70% ethanol and resuspended in 20 μl nuclease-free water. RNA concentration was determined by measuring absorbance at 260 nm. Quality of RNA was examined by gel electrophoresis on 0.8% agarose gel with TAE buffer prepared in DEPC treated water

For RNA experiments, all solutions were prepared in RNase free diethylpyrocarbonate (DEPC) treated water. Microcentrifuge and tips u

RNA extraction

Xanthomonas strains were grown in PS medium for 14-16 h at 28°C with continuous shaking at 200 rpm. 1 ml of bacterial cultures were ten-fold serially diluted in water and 100 μl volume of each dilution was plated on PS agar plates to get the colony forming units (CFUs). Similarly, 5 μl volume of each dilution was spotted on PS agar plates containing different concentration of streptonigrin and different detergents for intracellular iron and membrane sensitivity assay, respectively. Plates were incubated at 28°C and images were captured after 2-8 days of incubation depending upon m

Serial dilution plating and spotting assay

10% APS -30 μlTEMED -3 μlSDS loading buffer (2X)100 mM Tris-HCl (pH-6.8)20% (v/v) Glycerol4% (W/V) SDS0.02% Bromophenol Blue10% β-MercaptoethanolSDS-loading buffer was prepared as 2X stock solution in H2O and used at 1X concentration.SDS-PAGE running buffer14.4 g Glycine3.03 g Tris methylamine1 g SDSDissolved in H2O and volume was adjusted to 1L with H2O.Buffers for western blot analysisTransfer buffer (1 litre)14.4 g Glycine3.03 g Tris methylamine800 ml H2O 200 ml methanolBlocking and wash buffers (PBS-T)5% Fat-free milk0.05% Tween-20Volume was adjusted to 100 ml with1XPBS

Whole cell lysis buffer50 mM Sodium acetate 410 mg Sodium acetate anhydrous was dissolved in 80 ml H2O. pH was adjusted to 5.4 with glacial acetic acid and finally volume was adjusted to 100 ml with H2O.1 mM PMSF (phenylmethylsulfonyl fluoride) in isopropanol.Dialysis buffer50 mM Trizma basepH was adjusted to 7.5 by using concentrated HCl.Silver stainingFixing solution50% ethanol10% glacial acetic acid0.05% formaldehydeFinal volume was adjusted with sterile H2O.0.2% Silver nitrate solution (AgNO3)0.2 g AgNO3

0.075% formaldehyde (37% stock) Dissolved in 100 ml of H2O. Stored at 4°C for 1 hour in brown colored bottle.Developing solution 6% Sodium carbonate (Na2CO3)0.05% Formaldehyde (37% stock)0.02% Sodium thiosulphateStorage buffer50% EthanolSDS-PAGE30% Acrylamide solution29 g Acrylamide1 g Bis-acrylamideAcrylamide solution was prepared in H2O.Resolving gel mix (12%) (10 ml)H2O -3.3 ml30% Acrylamide:Bisacrylamide mix (29:1) -4 ml1.5 M Tris-HCl (pH-8.8) -2.5 ml10% SDS -100 μl10% Ammonium persulphate (APS) -100 μlN, N, N’,N’,-Tetramethylethylenediamine (TEMED) -4 μlStacking gel mix (5%, 3 ml)H2O -2.1 ml30% acrylamide:bisacrylamide mix (29:1) -500 μl1.5 M Tris-HCl (pH-6.8) -380 μl 10% SDS -30 μl

Buffers and solutions for protein extraction, analysis by SDS-PAGE (sodium dodecyl sulphate-polyacrylamaide gel electrophoresis) and silver staining

Rifr, Apr, Kmr, Gmr, Tetrand Spcrindicate resistant to rifampicin, ampicillin, kanamycin, gentamicin and spectinomycin, respectively.Table 2.2: List of oligonucleotides used in the study

hydrochloric acid, sulphuric acid, methanol, acetic acid, acetone and nitric acid were purchased from Fischer Scientific. Protease inhibitor tablets were procured from Roche. Hybond-P membranes for protein transfer were purchased from Amersham Biosciences. Taq DNA polymerase and Hi-fidelity Taq DNA polymerase were purchased from Thermoscientific and Larova, respectively. SYBR-green kit for real-time PCRwas procured from Qiagen and Thermoscientific. Superscript SS-III RT kit was obtained from Invitrogen. Random hexamers were obtained from Qiagen. Different restriction enzymes used for cloning and mutation generation were purchased from New EnglandBiolabs (NEB). Plasmid DNA purification, PCR purification, gel extraction and reaction clean up kits were procured from Qiagen. Medium components for bacterial culture viz., sucrose, agar, Luria Bertani (LB), Nutrient Agar (NA), peptone, yeast extract, beef extract, magnesium chloride hexahydrate (MgCl2.6H2O) and potassium sulphate (K2SO4) were purchased from Himedia. Table 2.1: List of strains and plasmids used in the study

Agarose, phenol, dimethyl sulphoxide (DMSO), sodium acetate, sodium carbonate, sodium bicarbonate, mangenese sulphate, tris methylamine, trizma base, sodium dodecyl sulphate (SDS), formamide, ethylenediaminetetraacetic acid (EDTA), glycerol, polyethylene glycol, tributyrin, ammonium persulphate, TEMED, acrylamide, bis-acrylamide, coomassie brilliant blue (CBB), β-mercaptoethanol, chloroform, formaldehyde, nuclease free water, diethylpyrocarbonate (DEPC), isopropanol, ferrozine, glycine, sodium lauryl sarcosine, carbonylcyanidep-trifluoromethoxyphenylhydrazone (FCCP), benzyl amino purine (BAP), ferrozine, tween-20, triton-X-100, aniline blue, trisodium citrate dehydrate, remazol brilliant blue-xylan (RBB-xylan), lactic acid, nicotinic acid, hexadecyltrimethyl ammonium bromide (HDTMA), p-nitrophenol, carboxymethyl cellulose (CMC cellulose), sodium phosphate dibasic, sodium phosphate monobasic, rubidium chloride, ferrous sulphate, ferric chloride, ammonium sulphate, 2,5-diphenyloxazol (PPO), 1,4-bis (5 phenyl 1,2-oxazole) Benzene (POPOP) and 2, 2-dipyridyl were purchased from Sigma Chemicals. Sodium hypochloride, disodium hydrogen orthophosphate dehydrate, sodium chloride, sodium hydroxid

Chemicals, kits and culture medium components

A total of 150 fungal and 150 bacterial isolates were screened qualitatively and quantitatively for their ability to produce the enzyme, tannase.

Screening and selection of potential tannase producers

Buffer pH range Stock Solutions Volume of Stock A + Stock BCitrate Phosphate 3–5 A: 0.1M solution of citric acid B: 0.2M solution of Na2HPO4pH 3: 39.8 ml A + 10.2 ml B made up to 100 ml pH 4: 30.7 ml A + 19.3 ml B made up to 100 ml pH 5: 24.3 ml A + 25.7 ml B made up to 100 ml Phosphate 6–8 A: 0.2M solution of NaH2P04 B: 0.2M solution of Na2HPO4 pH 6: 87.7 ml A + 12.3 ml B made up to 200 ml pH 7: 39 ml A + 61 ml B made up to 200 ml pH 8: 5.3 ml A + 94.7 ml B made up to 200 ml Tris - HCI 9 A: 0.1M solution of (HOCH2)3CNH2B: 0.1M HCI solution (16.16 ml of 11.35N HCI /L) pH 9: 70 ml A + 30 ml B made up to 200 ml Glycine - NaOH 10 A: 0.1M glycine B: 0.1M NaOH solution pH 10: 50 ml A + 32 ml B made up to 200 ml Phosphate hydroxide 11 A: 0.05M Na2HP04B: 0.05M sodium hydroxide pH 11: 91 ml A + 9 ml B Hydroxide Chloride 12 A: 0.05M KCI solution B: 0.05M KOH solution pH 12: 82 ml A + 18 ml B

Composition of buffers

Radioactive counts measured in2x106labelled C. glabratacells and lysates were considered as ‘input’ and ‘output’ values, respectively. Percentage adherence was calculated by following equation.%Adherence=Output radioactive countsInput radioactive countsX 100

Adherence of C. glabratacells to Lec2, Chinese hamster ovarian (CHO) cells, wasdetermined as described previously (Cormack et al., 1999). Briefly, Lec2 cells were seeded at a cell density of 5x105cells per wellin a 24-well tissue culture plate.Cells were incubated in a cell culture incubator (Thermo Scientific) set at 37°C and 5%CO2for 12 h. Post incubation, the medium was discarded in a reservoir and Lec2 monolayer was washed thrice with sterile 1X PBS without disturbing the monolayer. Lec2 cells were fixed with 3.7% para-formaldehyde for15 min followed by twoPBS washes. 1 mlof 1X PBS containing antibiotics, penicillin (100 units/ml) and streptomycin (100 μg/ml), was added to each well, plates were sealed with PARAFILM, Cole-Parmer(PM-996) and stored at 4°C until use.C. glabrata cells,to be tested for their adherence potential, were grown in CAAmedium for 24 h.100 μl of 24 h-grownculture was re-inoculated in fresh 5 ml CAAmedium containing 200 μCi of S35(Met:Cys-65:25) INVIVO PROTWIN label mix (JONAKI, India)in a 15 ml polypropylene tube.Cultures were allowed to grow for 16-20 h at 30°C with shakingat200 rpm to radiolabel the cells. Radiolabelled C. glabratacells were harvested by spinning down1 ml of labelled yeast cultures,andthe cell pellet was washed thrice with sterile 1X PBS to remove any residual S35(Met:Cys-65:25) labelling mix from the medium. Post washes, the pellet was resuspended in 1 ml PBS, OD600was measured andcell suspension of 0.4 OD600wasprepared.Next, 24well plates containing fixed Lec2 cells were taken out from 4°C and PBS from the wells wasdiscarded by inverting the plates. Wells were washed once with PBS and 2x106labelled yeast cells were added to eachwell, andincubatedfor 30 min at room temperature.Post incubation, plates were centrifuged at 1,000 rpm and the wells were washed thrice with 1X PBS to remove non-adherent C. glabratacells. Lec2 cells were lysed with 5% SDS in PBS by scraping the wells, lysates were collected and transferred to a vial containing scintillation fluid

Adherence assay

using the GENESPRING GX (Version 12.0) software,normalized to 75 percentile shift and represent the average of two hybridizations from biological replicates for each sample. Functional annotation of differentially regulated gene set(≥1.5 Fold change with p≤0.05)was performed using the GENESPRING GX (Version 12.0) softwareand GO terms with p<0.05 were considered as statistically significant. Using the REVIGO tool(http://revigo.irb.hr), redundant and significantly overlapping GO terms were removed and summarized. In REVIGO analysis, S. cerevisiaedatabase was chosen for GOterm sizes andtheallowed similarity value was set to 0.5(small).Additionally, to identify the overlap among differentially expressed genes, functional category analysis was performed usingthefungal specific annotation tool FUNGIFUN (https://sbi.hki-jena.de/FungiFun/FungiFun.cgi). Significantly enriched FunCat (Functional Catalogue) associated pathways were extracted usingthewhole C. glabratagenome as background and compared across differentially regulated gene sets. The parameters used for FUNGIFUN analysis were cut-off p=0.05; Fisher’s exact test; FunCatlevel 3. Raw data sets for this study are available attheGene Expression Omnibus database (http://www.ncbi.nlm. nih.gov/geo; accession no. GSE60741

Log-phase C. glabratacells were grown either in YNB or YNB medium supplemented witheither50 μMBPS(iron limiting) or 500 μMferric chloride (iron excess) for 2 h. Cells were spun down at 4,000 rpm for 5 min and washed twice with ice-cold DEPC-treated water. Total RNA was extracted usingtheacid phenolisolationmethod, resuspended in nuclease-free water and stored at -80°C. The frozen RNA samples were sent to Genotypic Technology Ltd., Bangalore (http://www.genotypic.co.in) wherein quality of RNA samples wasdetermined by examining the RNA integrity number (RIN) before performing microarray analysis. Next, the 8x15 GE Agilent array,comprised of 60mer oligonucleotides representing a total of 5,503 C. glabrataORFs (three replicates of each probe on average),was used for single colour microarray experiments.Datawereextracted

Microarray analysis

To perform immunoblotting or western blotting, appropriate amounts of total protein(ranging from 20-40 μg) were separated ona SDS-PAGE gel of 12%acrylamide concentration in Tris-Glycine-SDS gel running buffer. Protein separation was done at 70-100 V for 2-3 h using a MINI PROTEAN®3 electrophoresis unit (Bio-Rad). Followingseparation, proteins weretransferredto polyvinylidene difluoride (PVDF) membrane, using a Bio-Rad Mini Trans-Blot electrophoretic transfer unit in Tris-Glycine transfer buffer at 4⁰C. Before setting transfer assembly, PVDF membrane was first activated in 100% methanolfollowedby washesin the transfer buffer. The transfer assembly was set inaBio-Rad Mini gel holder cassette (170-3931)according to manufacturer’s instructions. The transfer time and current settings varied depending on the size oftheprotein of interest. Post transfer, membranes wereseparated from the assembly and kept for blocking intheblocking buffer (0.1 % Tween-20, 5% w/v fat-free skimmed milk in 1X TBS) for 1 h at room temperature with shaking. Next,membranes wereincubated with appropriate dilutions of primary antibodiesin the blocking buffereitherfor 3-4 h at room temperature or overnight at 4°C with gentle shaking. Post incubation,membranes were washed thrice with 1X TBS-T, 10 min each,with constant agitation. After washes, membraneswere incubated with appropriate dilutions of secondary antibodiesconjugated with horseradish peroxidase (HRP) for 1 h at room temperature with gentle shaking. Next, membranes were washed thrice with 1X TBS-T, 10 min each,with constant agitation. To visualize proteins, membranes were removed from TBS-T, and theHRP substrate ECL plus (Amersham Biosciences, RPN2232) was uniformly added on top of the membrane. Chemiluminescent signalswere captured in the western blot imaging system (FluorChemTME system)

For protein extraction, cells were spun down at 4,000 rpm for 5 min and washed with ice-cold water. The cell pellet was resuspended in 250-500 μl of homogenisation buffer which contained50 mM Tris (pH 7.5), 2 mM EDTA, 1 mM phenylmethylsulphonyl fluoride (PMSF) (serine protease inhibitor), 10 mM sodium fluoride (serine/threonine and acid phosphatases inhibitor), 1 mM sodium orthovanadate (Tyrosine and alakaline phosphatases inhibitor) and 1X protease inhibitor cocktail (Sigma, P 8215). The cell suspensison was transferred to a 1.5 ml centrifuge tube and equal amounts of glass beads (0.5 mm size) were added. Cells were lysed mechanically by bead-beatinghomogenizer (MP Biomedicals, FastPrep®-24) atthemaximum speed for 60 seconds, five times each,with intermittent cooling on ice.After lysis, tubes were punctured at the bottom with the helpofasurgical needle, and the lysed cell suspension was collected in a fresh microcentrifuge tubes by putting the punctured tubes on top of the fresh tubes and centrifuging them at 3,000 rpm for 10 min. The supernatant was transferred toafresh microcentrifugetubeandprotein concentrationwasestimated usingtheBCA protein assay kit (Thermo scientific). Protein preparations werestored at -20°C until use

Total protein extraction and immunoblotting

For complementation studies, C. glabrataORFs, CgFTR1(1.22 kb), CgFET3(1.91 kb), CgYFH1(0.53 kb), CgCCW14(0.64 kb), CgMAM3(1.91 kb)andCgHOG1(1.34 kb) were PCR amplified from wild-type genomic DNA using Phusion high-fidelity DNA polymerase and cloned down-stream of the PGK1promoter intothe XmaIand XhoI, XbaIand XmaI, XmaIand XhoI, BamHIand SalI, XmaIand XhoI, and BamHIand XmaIsites, respectively, in the CEN-ARS containing plasmid pGRB2.2 (pRK74). For over-expression studies, C. glabrataORFs, CgCCC1(0.95 kb), CgYAP5(1.05 kb)andCgMRS4(0.92 kb) were PCR amplified from wild-type genomic DNA using Phusion high-fidelity DNA polymerase and cloned down-stream of the constitutive promoter PDC1into the BamHI and SalI, XbaIand XmaI, and XmaI and XhoIsites, respectively, in the CEN-ARS containing plasmid obtained from Addgene (Addgene-ID 45323). All clones were verified by PCR and sequencing analysis

Cloning of C. glabrataORFs

PCR-positive transformants were inoculated in 10 ml YPD medium, allowedto grow for 12 handgenomic DNAwas isolated.Another round of PCR was performed using genomic DNA asatemplate toconfirm the gene deletion

A homologous recombination-based strategy was used to disrupt C. glabraraORFs witha cassette containing the nat1gene, which codes for nourseothricin acetyltransferase and imparts resistance to nourseothricin. Briefly, 5’-and 3’-UTR region (nearly 500-700 bp) of the gene to be deleted were amplified by PCR using wild-type genomic DNA as template. Both 5’-and 3’-UTR amplified products were fused to one half each ofthenat1gene amplified from theplasmid(pRK625). The two nat1-amplified fragments share about 300-350 bp complimentary region. To obtain fusion products, primers were designed insucha way thatthereverse primer for 5’-UTR and the forward primer for 3’-UTRof the gene of interestshare 20 bp complimentary region with the forwardprimer for 5’nat1fragment andthereverse primer for 3’nat1fragment amplification, respectively. The fused PCR products were co-transformed in to the wild-type strain and transformants were plated on YPD-agar plates. Plates were incubated at 30°C for 16 h to allow the homologous recombination between nat1fragments,and 5’-and 3’-UTR atthegenomic loci. Post incubation,cells were replica plated ontoYPD-agar plate supplemented with 200 μg/ml nourseothricin and incubated for another 24 h. Nourseothricin-resistant colonies were purified and verified for gene disruption viahomologous recombination by PCR using appropriate set of primers

Generation of C. glabratadeletion strains

For Yeast colony PCR, yeast cells were subjected to zymolyase (MP Biomedicals, 0832092) digestion to obtain thespheroplast. To perform zymolyase digestion, a digestion cocktail was prepared in 1XPBS consisting of zymolyase (2.5mg/ml) and sorbitol (1.2 M). The cocktail was dispensed in 0.2ml PCR tubes in 10 μl aliquots anda tip-full of yeast cells wasadded to these tubes. Tubes were incubated at 37°C for 2-3 h and 1 μl of digested mixture was used as a template in a PCR reaction

Yeast colony PCR

To perform restriction digestion of plasmid DNA and PCR-amplified DNA products, restriction enzymes were procured from NEW ENGLAND Biolabs(NEB). Restriction digestion was set in 50 μl reaction volume with appropriate buffer and 1X BSA. For ligation of DNA fragments obtained after restriction digestion, T4 DNA Ligase enzyme (NEB, M0202M) was used. All ligation reactions were set in 20 μl reaction volume containing 1X ligase buffer, 3-10 units of DNA ligase enzyme and vector to insert molar ratio of 1:3. The ligation mixture waseitherincubated at 16°C for 16h or at room temperature for 2-3 h. Post incubation, ligation reaction was inhibited by heatingtubes at 65°C for 15-20 min.2-5 μl of ligation mixture was used to transform ultra-competent E. coliDH5αcells

Restriction digestion and ligation

To extract DNA from agarose gels,the QIAquick® gel extraction kit (QIAGEN, 28706) was used. For purification of PCR amplified DNA products,the QIAquick® PCR purification kit (QIAGEN, 28106) was used. Clean-up of enzymatic reactions was performedusing the MinElute® Reaction Cleanup kit (QIAGEN, 28204). Allprotocolswere followed as per manufacturer’s instruction

Gel extraction, PCR purification and Reaction clean-up

Bacterial plasmid DNA was isolatedusing the QIAprep® spin Miniprep kit (QIAGEN, 27106). 10 ml of LB medium supplemented with appropriate antibioticswas inoculated withasingle bacterial colony and incubated at 37°C for 12-16 h. Cultures were spun down at 8,000 rpm for 5 min, supernatant was discarded and the cell pellet was processed to isolate plasmid DNA as per instructions given in the kit. DNA was eluted either in nuclease-free water or in elution buffer provided in the kit and stored at -20°C until use

Plasmid isolation

were chosen for qPCR. For all qPCR reactions,0.4 μl of cDNA template was used in a 20 μl reaction volume. Reactionswere performed anddata wereanalysed in ABI7500 real-time qPCR machine. Amplified products were run on 2% agarose gel to confirm amplification ofthecorrect size product. CTvalues of respective products were normalized with corresponding CTvalue of the housekeeping gene CgACT1. Relative change in expression was determined by comparative CTmethod,also referred as 2-∆∆CTmethod, utilizing following equation.Fold change upon treatment=2-∆∆CT∆∆CT=∆CT Treated-∆CT Untreated∆CTTreated= CTvalue for gene of interest upon treatment-CTvalue of internal control (CgACT1)upon treatment∆CTUntreated= CTvalue for gene of interest without treatment-CTvalue of internal control (CgACT1)without treatmentThe reaction cycling conditions were as follows1)95°C for 10 min (initial activation)2)95°C for 15 sec (denaturation)3)55°C for 30 sec (annealing)4)72°C for40 sec (extension)5)Go to step 2 (40 cycles)6)72°C for 10 min (final extension)

MESA GREEN qPCR mastermix (RT-SY2X-03+WOULR) supplied by Eurogentech was used in all qPCR experiments. Primers for real-time qPCR experiments were designed by using the Primer3 plus software to obtain 120-200 bp amplification products. Standardization of optimaltemplate and primer concentrationconditionswas done in a PCR reaction and concentrations resulting in good amplification withoutprimer dimers

Quantitative Real-time PCR(qPCR)

Reverse transcriptase “Superscript III” (Invitrogen, 18080-051) was used to perform cDNA synthesis. Briefly, 500 ng of DNase I-digested RNA was incubated with 1 μl of 10 mM dNTP and 50 μM oligo(dT) at 65°C for 5 min in a 10 μl reaction mixture followed by cooling on ice for 5 min. Post incubation, 10 μl of cDNA synthesis mixture was added which contained 2 μl of 10XRT buffer, 4 μl of 25 mM MgCl2, 2 μl of 0.1 M DTT, 1 μl of RNase out (40 units) and 1μl of Superscript III (200 units). Tubes were incubated at 50°C for 1 h and thereaction was terminated at 85°C for 5 min. The quality of synthesized cDNA was checked by using it as a template in a PCR reaction to amplify the housekeeping gene CgACT1. Amplification of CgACT1was indicative of proper cDNA synthesis

Complementary DNA (cDNA) synthesis

Deoxyribonuclease I (DNase I) enzyme (Invitrogen) was used to remove the DNA contamination from RNA samples,if any. Briefly,1 μg of RNA was subjected to DNase I digestion by using 1 U of DNase I in a 10 μl reaction mixture which contained 1X DNase I buffer and appropriate volume of water. The reaction mixture was incubated at room temperature for 15 min. Post incubation,to inhibit DNase I enzyme activity,1 μl of 25 mM EDTA was added to the reaction mixture and tubes were heated at 65°C for 10 min. DNase I-digested RNA samples were used as template to perform PCR for the amplification of CgACT1geneandabsence of amplification product was used as criterion toconfirmproper DNase I digestion and lackof DNAcontaminationin the RNA sample

DNase I digestion

microcentrifuge tube. For precipitation of RNA, 1/10thvolume of 3 M sodium acetate (pH 5.3) and 2.5 volume of 100% ice-coldethanol was added. In order to facilitate precipitation, tubes werekept at -20°C for 20 min. Tubes were centrifuged at 13,000 rpm for 10 min in a refrigerated centrifuge. The RNA pellet was washed with 70% ethanol,resuspendedin 100-200 μl of nuclease-free water and stored at -20°C untiluse.Care was taken to keep allreagents and tubes on ice to maintain the cold temperature throughout theRNA extractionprocess

All reagents required for RNA extraction were preparedin DEPC-treated water. RNasecontamination from non-autoclavable items wasremoved by wiping them with RNaseZap® (Ambion). Total RNA from yeast cells was extractedusing acid phenolextractionmethod. Briefly, yeast cells were grown underappropriate conditions and at suitabletime points,cells were harvested by centrifugation at 4,000 rpm for 5 min. The cell pellet was washed twice with ice-cold DEPC-treated water, resuspended in 350 μl of AE buffer and transferred toa1.5 ml microcentrifuge tube. To this,40 μl of 10% SDS and 400 μl of acid phenol (pH 4.3) was added. The cell suspension was mixed well by vortexing thrice, short pulsesof10 seconds each,and incubated at 65°C for 15 min with continuous agitation at 800 rpm. Post incubation, cells were kepton ice for 5 min and centrifuged at 13,000 rpm in a refrigerated centrifuge set at 4°C for 10 min. After centrifugation, aqueous layer was transferred to a new1.5 ml microcentrifuge tube and 400 μl of chloroform was added. Tubes were mixed well by gentlyinverting them 4-5 times and centrifuged at 13,000 rpm for 10 min. The aqueous layer was separated and transferred to a new1.5 ml

Total RNA isolation

This method was used to isolate highly pure genomic DNA. Briefly, 10 ml overnight grownC. glabratacultures were spun downandwashed with 10 ml sterile water. Washed cells wereresuspended in500 μl sterile water and transferred toa1.5 ml microcentrifuge tube. Tubes were spundownat 4,000 rpm for 5 min, supernatant was discarded andcell pellet was resuspended in 500 μl of buffer containing 100 mM EDTA and 5% β-mercaptoethanol and incubatedat 42°C for 10 min. Post incubation, cells were spun down at 4,000 rpm for 5 min and resuspended in freshly prepared Buffer B. To this, one tip-full of lyticase (Sigma, L4025) was added and incubated at 37°C for 1 h.After incubation, spheroplasts were collected by spinning downtubes at 6,000 rpm for 5 min, supernatant was discarded and the pellet was resuspended in 500 μl of Buffer C. DNA was extracted twice with 500 μl of PCI (25:24:1) solution and the aqueous layer was transferred toa new1.5 ml microcentrifuge tube. To this, 2.5 volume of absolute ethanol and 1/10thvolume of 3 M sodium acetate (pH 5.3) wereadded. Tubes were spundownat 13,000 rpm for 10 min, DNA pellet was resuspended in 200 μl of 1X TE buffer containing0.3 μl of RNase cocktail (Ambion) and incubated at 37°C for30 min. DNA was precipitated again by adding absolute ethanol and sodium acetate as mentioned above. DNA pellet was washed once with 70% ethanol, centrifuged at 13,000 rpm for 10 min, air-dried at room temperature and was resuspended in 100-200 μl of 1X TE buffer by gently tapping the tube. DNAwas stored at -20°C until use

Spheroplast lysis method

Yeast genomic DNA was isolated by mechanically lysing the yeast cells. Briefly, 10 ml of overnight grown yeast culture was transferred toa 15 ml centrifuge tube andcells were spun down at 4,000 rpm for 5 min. Media was decanted and cells were washed with 10 ml sterile water. Washedcells were resuspended in 500 μl of Buffer A and transferred to a 1.5 ml microcentrifuge tube. Tubes were incubated at 65°C for 15 min. Post incubation,500 μl of PCI (25:24:1) solution was added. To this, 0.5 g of 0.5 mm glass beads were added and cells were lysed mechanically in a bead-beatinghomogenizer (MP Biomedicals,FastPrep®-24) thrice, 45 seceach, with intermittent cooling on ice. Tubes were spun at 12,000 rpm for 5 min and the aqueous layer was transferred to a new 1.5 ml microcentrifuge tube. To this, 500 μl of PCI solution was addedand mixed gently by inverting the tubes.Tubes were centrifuged again at 12,000 rpm for 5 min and aqueous layer was transferred to another 1.5 ml microcentrifuge tube. Next, 2.5 volume of absolute ethanol was added to the aqueous layer, mixed well and centrifuged at 13,000 rpm for 10 min. Supernatant was decanted and the DNA pellet was washed once with 70% ethanol and centrifuged at 13,000 rpm for 10min. Washed DNA pellet was air-dried and dissolved in 100-200 μl of 1X TE buffer by gently tapping the tubes

Glass bead lysis method

Total protein extraction and immunoblotting

For complementation studies, C. glabrataORFs, CgFTR1(1.22 kb), CgFET3(1.91 kb), CgYFH1(0.53 kb), CgCCW14(0.64 kb), CgMAM3(1.91 kb)andCgHOG1(1.34 kb) were PCR amplified from wild-type genomic DNA using Phusion high-fidelity DNA polymerase and cloned down-stream of the PGK1promoter intothe XmaIand XhoI, XbaIand XmaI, XmaIand XhoI, BamHIand SalI, XmaIand XhoI, and BamHIand XmaIsites, respectively, in the CEN-ARS containing plasmid pGRB2.2 (pRK74). For over-expression studies, C. glabrataORFs, CgCCC1(0.95 kb), CgYAP5(1.05 kb)andCgMRS4(0.92 kb) were PCR amplified from wild-type genomic DNA using Phusion high-fidelity DNA polymerase and cloned down-stream of the constitutive promoter PDC1into the BamHI and SalI, XbaIand XmaI, and XmaI and XhoIsites, respectively, in the CEN-ARS containing plasmid obtained from Addgene (Addgene-ID 45323). All clones were verified by PCR and sequencing analysis

Cloning of C. glabrataORFs

PCR-positive transformants were inoculated in 10 ml YPD medium, allowedto grow for 12 handgenomic DNAwas isolated.Another round of PCR was performed using genomic DNA asatemplate toconfirm the gene deletion

A homologous recombination-based strategy was used to disrupt C. glabraraORFs witha cassette containing the nat1gene, which codes for nourseothricin acetyltransferase and imparts resistance to nourseothricin. Briefly, 5’-and 3’-UTR region (nearly 500-700 bp) of the gene to be deleted were amplified by PCR using wild-type genomic DNA as template. Both 5’-and 3’-UTR amplified products were fused to one half each ofthenat1gene amplified from theplasmid(pRK625). The two nat1-amplified fragments share about 300-350 bp complimentary region. To obtain fusion products, primers were designed insucha way thatthereverse primer for 5’-UTR and the forward primer for 3’-UTRof the gene of interestshare 20 bp complimentary region with the forwardprimer for 5’nat1fragment andthereverse primer for 3’nat1fragment amplification, respectively. The fused PCR products were co-transformed in to the wild-type strain and transformants were plated on YPD-agar plates. Plates were incubated at 30°C for 16 h to allow the homologous recombination between nat1fragments,and 5’-and 3’-UTR atthegenomic loci. Post incubation,cells were replica plated ontoYPD-agar plate supplemented with 200 μg/ml nourseothricin and incubated for another 24 h. Nourseothricin-resistant colonies were purified and verified for gene disruption viahomologous recombination by PCR using appropriate set of primers

Generation of C. glabratadeletion strains

For Yeast colony PCR, yeast cells were subjected to zymolyase (MP Biomedicals, 0832092) digestion to obtain thespheroplast. To perform zymolyase digestion, a digestion cocktail was prepared in 1XPBS consisting of zymolyase (2.5mg/ml) and sorbitol (1.2 M). The cocktail was dispensed in 0.2ml PCR tubes in 10 μl aliquots anda tip-full of yeast cells wasadded to these tubes. Tubes were incubated at 37°C for 2-3 h and 1 μl of digested mixture was used as a template in a PCR reaction

Yeast colony PCR