E. coli DH5α ultra-competent cells were transformed with plasmid DNA by heat shock at 42 ̊C for 90 sec as described previously in Molecular Cloning-A Laboratory Manual (Sambrook and Russell,2001). Bacterial transformants were selected on LB agarmediumcontaining appropriate antibiotics. Transformants obtainedwere colony purified on LB plates containing antibiotics.Presence of the desired insertwas first verified by colony PCR followed by PCRusing extracted plasmid DNA as template

Bacterial transformation

suspension was kept on ice for 10 min and 50 μl volume was aliquoted to chilled sterile microcentrifuge tubes. Cellswere immediately snap-frozen in liquid nitrogen and stored at -80 ̊C

A single colony of E.coli DH5-α strain was inoculated in 10ml LB medium and incubated at37 ̊C for overnight. 4 ml of thisovernight culture was inoculated in 2 lt SOB medium and incubated at 18 ̊C till theOD600reaches to 0.5. Cells were harvested by centrifugation at 2,500 g for 10 min at 4 ̊C and washed gently in 80 ml ice-cold Inoue transformation buffer. Cells were collectedby centrifugation at 2,500 g for 10 min at 4 ̊C and gently resuspended in 20 mlice-cold Inoue transformation buffer. To this cell suspension, 1.5 ml sterile DMSO was added and swirled gently. Cell

E. coli DH5α ultra-competent cells preparation

All experiments in this studywere performed with log-phase cellsunless otherwise mentioned. For obtaining log-phase cells, overnight YNB-or YPD medium-grown yeast cellswerere-inoculated in fresh YNB or YPD medium to an initial OD600of 0.1-0.2.Cells were incubated at 30 ̊C with shaking at 200 rpmtill the OD600reached to 0.4-0.6 OD. After incubation, log-phase cellswere collected bycentrifugation at 4,000 rpm for 3 min,washed once with the same medium and usedforfurtheranalysis

Cultivation of logarithmic-phase cell culture

C. glabratastrains were grown overnighteither in YPDor YNBliquid mediumat 30 ̊C with shaking at 200 rpm. Cells were harvested and suspended in 1X PBS to a final OD600of 1.0.Five 10-fold serial dilutions of cell suspension wereprepared in PBS and3-4μlwasspotted on YPD/YNBplates containing various test compoundsusing a multi-channel pipette.Plates were incubated at 30 ̊C and growth profileswererecorded after2-4days

Serial dilution spot assay

Yeast cell viability was measured by plating appropriate dilutions of cell cultureonYPD plates at various time intervalsduringgrowth.Cell suspension was diluted in1X PBS. YPD plates were incubated at 30 ̊C for 2-3 daysand total colony forming units(CFUs)were calculated by counting the number of coloniesthat appeared onYPDplatesand dividing that number by anappropriate dilution factor

Yeast cell viability assessment viacolony forming unit (CFU) assay

preparedin appropriate solvents, sterilizedby autoclaving or filtrationand stored at appropriate temperature

For growth analysisof C. glabratastrains, a single colony from YPD or YNBagar mediumwas inoculated in appropriate liquid medium and incubated at 30 ̊C with shaking at 200 rpmfor 14-16 h. This overnight grown culture was used toinoculatetest medium to an initial OD600of 0.1to 0.3.Optical density/Absorbance of the cell suspensionwas measured using Ultraspec 2100 pro UV/visible spectrophotometer (Amersham Biosciences) at600nmat regular time-intervals up to a period of 96 h.Absorbance values were plotted with respect to time. Generation time of yeast strains wascalculated fromthe logarithmic (log) phase of cellgrowth. Growth profilesbetween 4 (t1)and 8 h(t2)time interval wereconsideredfor calculationof generation time usingfollowing formula. Generationtime(G)= (t2-t1) x {log (2)/ [log (Bf/Bi)]}G= Generation time in ht1=Initial timepoint taken for analysist2 = Final timepoint taken for analysisBf= Number of cells at time t2(calculated on the basis of OD600values, wherein1 OD600of C. glabratacorresponds to 2 X 107cells.)Bi= Number of cells at time t1(calculatedas mentioned above)Severalyeast strains used in this study were analysed for their susceptibility to variouschemical compounds,drugsand metal ions. For this purpose, stock solutions were

Growth assayand measurementof generation time

mM final concentration) and pH was adjustedto the desired valueby addition of HCl or NaOH. Medium was sterilized by autoclaving.YNBagar plates ofdifferent pHwereprepared by mixing equal volume of separately autoclaved 4% bacto-agar solution and2X varied pH-adjusted-YNB liquidmedium.All routine sterilization of mediumand solutionswas either carried outby autoclaving at 121 ̊C for 15-20 minat highpressure condition(15 psi)or filtration with 0.2 μmpolyvinylidene fluoride(PVDF) membranefilter unit (Millex®-GV, Millipore).Both yeast and bacterial strains were stored as frozen 15% glycerol stock at -80 ̊Cfor extendedlifetime

C.glabratastrains were maintainedeither on rich YPDor synthetically-defined YNB medium. C.glabratacells were routinely culturedat 30 ̊Cwith shaking at 200 revolutions per min(rpm)unless otherwise mentioned. Forgrowthexperiments, C. glabratastrains were freshly revived on YPDmediumfrom glycerol stocks.Escherichia coliDH5α bacterial strainwasused for plasmid transformation and propagationpurposes and maintained on LB medium.E.coliBW23473 bacterialstrainwas used to rescue Tn7transposon cassette from C. glabrataTn7insertion mutantsand maintained on LB medium. Bacterial strainsharboring plasmids were maintained on LBagar plates supplemented withappropriate antibiotics.For plasmid isolationpurpose,bacterial strains were grown overnight in liquid LB brothcontainingappropriate antibiotics at 37 ̊C with shaking at 200 rpm. Forpreparation of the solid medium, 2%bacto-agar was added to the mediumand autoclaved. To prepare medium of different pH, YNB mediumwas either buffered with citrateor HEPESbuffer (100

Strainsand culture conditions

Microbiological techniques

10 mM Tris-HCl (pH 8.0)1 mM EDTA Tris-Acetic acid EDTA (TAE) buffer:40 mM Tris base 0.5 M EDTApH was adjusted to 8.5 with glacial acetic acid.This was prepared as a 50 X stock solution and used at a 1 X concentration. Tris-Borate EDTA (TBE) buffer:90 mM Tris-borate 2 mM EDTA (pH 8.0) pH was adjusted to 8.3withHCl.This was prepared as a 10 X stock solution and used at a 1 X concentration.Both TAE and TBE were used asstandard gel electrophoresis buffers.HEPES buffer:This was used to prepare YNB medium of different pH.1M HEPESpH was adjusted to 7.5withNaOH.Bufferwas filter-sterilized and stored in an amber-coloured bottle. Citrate buffer(0.1M, pH 5.5):4.7 volume of 0.1 M Citric acid 15.4 volume of 0.1 M Sodium citrate

Phosphate-Buffered Saline (PBS):137 mM NaCl 2.7 mM KCl10 mM Na2HPO42 mM KH2PO4pH was adjusted to 7.3.This was prepared as a 10 X stock solution andused at a 1 X concentration.Tris-HCl buffer:0.5 M TrizmaBase pH was adjusted to7.6 using concentrated HCl.This was prepared as a 10 X stock solution andused at a 1 X concentration.Tris-EDTA (TE)buffer:

Common buffers

Luria Bertani (LB):0.5% Yeast Extract1% Tryptone 1% NaCl LB-ampicillinand LB-kanamycin plates:LB medium50 μg/ml ampicillin30 μg/ml kanamycinSuper Optimal Broth (SOB): 0.5% Yeast extract2% Peptone 10 mM NaCl2.5 mM KCl10 mM MgCl210 mM MgSO4

Bacterial medium

All C. glabratastrains and plasmids used in this study are listed in Tables 2.1 and 2.2, respectively.Table 2.1: List of yeast and bacterial strains used in this study

Strains and plasmids

A single colonyof desired C. glabratastrainwas inoculated in YPD-liquid mediumand grown for 14-16 h. 50 μl overnight culture was inoculated inYPD-liquid mediumfor 4 h. Log-phase-grownyeast cells were harvested,washedwith PBSandwereinoculated atinitial OD600of 2 and 4,into YNB-dextrose and YNB-sodium acetate liquid medium,respectively.After 4 hincubation,yeast cells were harvested by centrifugation at 2,500g for 5 minand treated with 1.2 M zymolyasefor 1 hto obtain spheroplasts.Post zymolyase treatment, spheroplasts were resuspended in 100 μl resuspension bufferandanequal amount of 0.25 mm glass beadswasadded to lyse the spheroplasts. Using bead beater apparatus, spheroplasts were lysed and protein concentration in spheroplast lysateswas determined usingbicinchoninic acid assay (BCA) method and samples were stored at -20ºC till further use

Preparation of cell lysate

Experiments involving mice were conducted at VIMTA Labs Limited, Hyderabad in strict accordance withguidelines of The Committee for the Purpose of Control and Supervision of Experiments on Animals (CPCSEA), Government of India. The protocol was approved by the Institutional Animal Ethics Committee (IAEC) of the Vimta Labs Ltd. (IAEC protocol approval number: PCD/OS/05). Procedures used in this protocol were designed to minimizeanimalsuffering

Ethics statement

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

Bacterial strainEscherichia coli DH5αused for cloning purposewas revived on LB medium and grown at 37°C withcontinuous shaking at 200 rpm. LB medium was supplemented with appropriate antibiotics to growbacterial strains carrying plasmids. AnotherE. coli strain,BW23473,was used to rescue the Tn7transposon cassette from C. glabrataTn7insertion mutants. For plasmid DNA purification, bacterial strains were grown overnight in LB broth medium containingsuitable antibiotics

C. glabratastrains were routinely grown either in rich YPD medium or synthetically-defined YNB medium at 30°C withcontinuous shaking at 200 rpm unless otherwise stated. In general, C. glabratafrozen glycerol stocks wererevivedonYPD medium by streaking and allowed to grow for 1-2 days. C. glabratastrainsharboringthe plasmid with URA3as selectable marker were revived onCAA medium.To prepare liquid cell culture, single colony of eachC. glabratastrainwasinoculated either in YPD or YNB broth mediumand grown for 14-16 h. C. glabratastrains streaked on plates were storedat 4°C fora maximum period of2 weeks

Strains and culture conditions

To collectmacrophage-internalized yeast cellsfor RNA and protein extraction, 107THP-1 monocytes were seeded in 100 mm cell culture dishes and treated with PMA. PMA-differentiated THP-1 macrophages were infected with appropriateC. glabratastrainsto a MOIof 1:1. Equal numberof C. glabratacells wasinoculated inRPMI medium as control. Two hourspost infection,non-phagocytosed yeast cells were removed by washing THP-1 macrophages thrice with PBS. At different time points, culture dishes were washed twice with chilled PBS and 2 mlchilled sterile water was added toeach dish to lyse the macrophages. Corresponding cultures grown in RPMI medium were transferred to50 ml polypropylene tubesand transferred on ice. Lysates were collected by scrapping the macrophage monolayer and transferred to50 ml polypropylene tubes.RPMI-grown and macrophage-internalized C. glabratacells were harvested by centrifugation at 2,500g for 8 min. Macrophage cell debris were removed frommacrophage-internalized cells by repeated washing with chilled sterile water. Harvested C. glabratacells were stored at -20ºC till further use

Harvesting of macrophage-internalized C. glabratacellsfor RNA and protein extraction

undertissueculture conditionsfor 45-60min andfixed in 3.7% formaldehydeas described earlier.For DAPI staining, Vectashield mounting medium containing DAPI was used and slides were visualized under confocal microscope.For heat killing, yeast cells were harvested from 1 ml culture, washed, resuspended inPBS andwere incubated at 95°C for 5 min

PMA-treated THP-1 macrophages were infected with C. glabratacells to a MOIof 1:1 in four-chambered slides and incubated at 37°C and 5%CO2. After 1 hcoincubation, each chamber was washed thrice with PBS to eliminate extracellular yeast cellsand medium was replaced with fresh prewarmed RPMI medium containing100 nM Lysotracker Red DND-99.Infected THP-1 macrophageswere incubated

Lysotracker staining

For confocal microscopyanalysis, 5X105THP-1 cells were seeded and treatedwithPMA in 4-chambered slides. Differentiated THP-1 macrophageswere infected either with FITC-labeled or GFP-expressingC.glabratastrains to a MOIof 1:1. At different time intervals, medium was aspirated out from each chamber of 4-chambered slides and chamberes were washed twice with PBS. To fixthe infected macrophages,500 μlformaldehyde(3.7%) was added gently toeach chamber andincubated for 15 minat room temperature. Each chamber of the slide was washed twice withPBS to remove formaldehyde solution completely. To permeabilize the fixed cells, 500 μl Triton-X (0.7%) was dispensed toeach chamber and slide wasincubated at room temperature for 5 min. Chambers of the slide werewashed twice with PBS, separated from the slideusing a chamber removal device andwere air dried. Coverslips were placed onslides using Vectashield mounting mediumand bordersweresealed withnail paint. Slides werestored at 4°C until used forfluorescence imaging

Fixing of PMA-treated THP-1 macrophages

THP-1 cells were seeded ina 24-well tissue culture plate to a celldensity of 1 million cells per well,treated with PMA and were infected with yeast cells to a MOIof 10:1. Two hours post infection, cells were washed thrice with PBS and medium was replacedwith fresh prewarmed RPMI medium.Plates wereincubatedat 37ºCfor 24 h. Supernatants were collected,centrifuged at 3,000 rpm for 5 minto get rid of particulate matter,if any, andwerestored at -20°C until use. Estimation of different cytokines wasperformed using BD OptEA ELISA kits as per the supplier’s instructions

Cytokines measurement

Forinfection of THP-1 cells with single C. glabratastrain, PMA-treatedTHP-1 monocytes were seeded in 24 wellcell culture plate toa seeding density of 1 million cells per well. To prepare C. glabratacells for macrophage infection, single colony of the desiredstrain wasinoculated in YPD medium and allowed to grow for 14-16 hat 30°C. C. glabratacellsfrom 1ml overnight culture were harvested, washed with PBS andcell density was adjustedto 2X107cells/ml.50 μl of thisC. glabratacell suspension wasinfectedto macrophages to a MOIof 10:1. Two hours post infection, infected THP-1 macrophages were washed thrice with PBS to removenon-phagocytosed yeast cells and medium was replacedwith fresh prewarmed medium. Atdifferent time points post infection,infected THP-1 macrophages were washed with PBS three timesandlysed in 1 mlsterilewater. Lysates were collected by scrapping the wells with a micropipette tip, diluted in PBS and appropriatelysatedilutions were platedon YPD agar medium. Plates wereincubated at 30°C and colony forming units (CFU) were counted after 1-2 days. Final CFUs per ml were determined by

multiplying CFUs with dilution factor and fold-replication was determined by dividing the CFUs obtained at 24 h time-point by 2 h CFUs

Single infection assay

THP-1 monocytes were treated with phorbol myrsitylacetate (PMA) to differentiate them to macrophages(Tsuchiya et al., 1982). For PMA treatment, THP-1 cells grown upto 70-80% confluencewere harvested from the culture dishes at 1,000 rpm for 3 min. Harvested THP-1 cells were resuspended in 5-10 ml fresh and prewarmed complete RPMI medium. 100μlof thiscell suspensionwasappropriatelydilutedinPBS and numberof viable cells was determined by trypan blue stainingusing hemocytometer. Cell suspension was diluted with prewarmed RPMI medium to a final density of 106cells/ml. PMA was added to this THP-1 cell suspension to a final concentration of 16 nM and mixedwell.PMA-treated THP-1 cellswere seeded either in 24-well cell culture plate or culture dishes and transferred to the incubator set at 37°C and 5%CO2.After 12 hincubation, medium was replaced with fresh prewarmed medium and cells wereallowed to recover for 12 h

Treatmentof THP-1 monocytic cells with phorbol myrsityl acetate

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

To isolate primary peritoneal macrophages, 6-8 week old BALB/c mice were injected with 3% (w/v) thioglycollate broth (0.55% dextrose, 0.05% sodium thioglycollate, 0.5% sodium chloride, 0.05% agar)intraperitonealy (I.P. 50 μl/g body weight). After five days of injection, mice were euthanized by CO2inhalationand peritoneal macrophages were harvested byflushing the peritoneal cavity (lavage) with 10 mlDMEM medium(Zhang et al., 2008)

Isolation of primary (peritoneal) macrophages from BALB/c mice

THP-1 andLec-2 cell lines were obtained from ATCC (American Type Culture Collection). THP-1 and Lec-2 cells were cultured and maintained in RPMI-1640 and α-MEM media,respectively, supplemented with 10% heat inactivated fetal bovine serum, 2 mM glutamine and antibiotics (100units/ml of penicillin and 100μg/ml of streptomycin). Both cell lines were maintained at 37°C and 5% CO2in Thermo-Scientific cell culture incubator. After every 2-3 days, spent medium was replaced with fresh,pre-warmed medium. For splitting the culture, cells were harvested at 1,000 rpm for 3 min. Spent medium was discarded and cells were resuspended in 4-6 ml fresh prewarmed medium. Finally, 3-4 million cells were resuspended in 12mlmedium in 100 mm culture dishes.Cellswere cultured and maintained in tissue culture incubatorat37°C and 5% CO2

Cell lines andculture conditions

Animal cell culture methods

Stripping solutionfor DNA1% SDS0.1% SSCDesired volume was adjusted with sterile water. Alternatively, 0.4 M NaOH was also used to stripthe bound probes fromnylon membranes.HEPES [4-(2-Hydroxyethyl)piperazine-1-ethanesulfonic acid] buffer1 M HEPESpH was adjusted to 7.5 with NaOH.HEPES was used as a buffering agent for preparing plates of YNB medium of different pH. Buffer was filter-sterilized and stored in an amber-coloured bottle.INOUE transformation buffer10 mM PIPES15 mM CaCl2.2H2O250 mM KCl55 mM MnCl2.4H2OpH was adjusted to 6.7 with 1 N KOH.Yeast transformation reagents1 M Lithium acetate 50% Polyethylene glycol2 mg/ml carrier DNADimethyl sulfoxide (DMSO)Zymolyase cocktail buffer for yeast colony PCR2.5 mg/ml Zymolyase1.2 M SorbitolZymolyase buffer was prepared in 1X PBS

pH was adjusted to 8.5 with glacial acetic acid.TAE buffer was prepared asa50Xstock solution and used at 0.5X concentration.Alkaline denaturing solution for DNAfor membrane preparation0.5 M NaCl0.25 M NaOHVolume was adjusted with sterile water.Denhardt’s solution (50X)1%Ficoll-4001% Polyvinyl pyrollidone1% Bovine serum albuminVolume was adjusted with water and solution was stored at -20°C.Saline Sodium Citrate (SSC) buffer(20X)3.0 M Sodium chloride0.3 M Sodium citrate Volume was adjusted with water and solution was sterilized by autoclaving.Prehybridization Buffer5X SSC5X Denhardt’s solution50% Filtered formamide1% SDSVolume was adjusted with sterile water.Post hybridization wash buffersWash buffer 12X SSC0.1% SDSWash buffer21X SSC0.1% SDS

Phosphate-Buffered Saline (PBS)137 mM NaCl2.7 mM KCl10 mM Na2HPO42 mM KH2PO4pH was adjusted to 7.3 before autoclaving.PBS was prepared as a 10X stock solution and diluted to 1X concentration before autoclaving.Tris-HCl buffer0.5 M Trizma BasepH was adjusted to 7.6 using concentrated HCl.Tris-Cl buffer was prepared as a 10Xstock solution and used at a 1X concentration.Tris-EDTA (TE) buffer10 mM Tris-HCl (pH 8.0)1 mM EDTATris-Acetic acid EDTA (TAE) buffer40 mM Tris base0.5 M EDTA

Common buffers

Yeast extract Peptone Dextrose (YPD)1% Yeast extract2% Peptone2% DextroseYeast Nitrogen Base (YNB)0.67% Yeast Nitrogen Base2% DextroseFor alternate carbon source utilization experiments, dextrose was replaced withother carbon sourcesviz.,sodium acetate, ethanol, oleic acid, glycerol and citric acid.Yeast Nitrogen Base (YNB) without ammonium sulphate and amino acids0.17% Yeast Nitrogen Base2% DextroseCasamino Acid (CAA)0.67% Yeast Nitrogen Base2% Dextrose0.6% Casamino acidsFor preparing plates, 2% agar was added tothe medium before autoclaving

Yeast media

Strains and plasmids

All C. glabrataand bacterial strains and plasmids used in this study are listed in Table 2.1

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

Total RNA was isolated by TRIzol method using the manufacturer’s protocol. Briefly, medium was removed from culture dish and recommended amount of TRIzol wasadded directly on to the dish and kept at room temperature for 5 minutes for lysis of cells. The cellular homogenate was then transferred to a 1.5ml microcentrifuge tube. For each mlof TRIzol, 200μl of chloroform was added and tubes were shaken vigorously for 10 seconds to completely dissociate the nucleoprotein complexes, followed by vortexing for about 30 seconds. The mixture was kept for 3-5 minutes at room temperature and then centrifuged at maximum speed of 12,000 rpm for 10 minutes. The upper aqueous phase was transferred into a fresh micro centrifuge tube and RNA was precipitated by adding 500μl of iso-propanol. The RNA pellet was obtainedby centrifugation at 12,000 rpm for 30 minutes at 4°C. The pellet was washed with 1ml of chilled 70% ethanol followed by centrifugation at 12,000 rpmfor 5minutes. The supernatant was removed and the pellet air-dried for about 5 minutes. The pellet was resuspendedin 30-50μl RNase free deionisedwater and dissolved at 55ºC followed by quantificationusingnanodrop spectrophotometerfor further use.The RNA integrity was checked by evaluating the 18S and 28S rRNA signals by running 1μl of total RNA on denaturing agarose gel stained with ethidium bromide

Total RNA isolation from cultured cells

nvolved use of GFP based vector system, the expression of the transgene was visualized under fluorescent microscope with excitation filter of 485+20 nm

Transient transfection of plasmid DNA in cellswas performed usingLipofectamine 2000transfection reagentaccording to manufacturer’s protocol. Briefly, 0.5 to 1million cellswere seeded in a 35mm tissue culture dish one day prior totransfection. For each 35mm dish, 4μg DNA was mixed in 250μl of Opti-MEMin one polypropylene tube. In another tube 10μl of Lipofectamine 2000 was diluted in250μl Opti-MEM and incubated at room temperature for 5 minutes. DNA and Lipofectamine 2000 were mixed together and allowed to form complexes for 30minutes at room temperature. Meanwhile, the adherent cells were washed twicewithPBS and 1ml of Opti-MEM was added. 500μl of complexes were then added to each dishcontaining cells and medium. After 6-8 hrs, the medium containing complexes wasremoved and complete medium was added and transgene expression was evaluated 24-48 hrs after transfection. Since most of the experiments

Transient transfection in adherent cells

Themixture is incubated in a water bath at 37⁰C for 15 min and afterwards transferred on ice and 4μl of DNA loading buffer is added. The samples were then run on a polyacrylamide gel electrophoresis which had been pre-run for 30 min. Electrophoresis was carried out at 4⁰C for 3h till the bromophenol blue migrated to 2cm above the bottom of gel. The gel was taken out and kept on Whatman filter paper sheet and covered by saran wrap followed by drying in a gel dryer at 80⁰C for 1h under suction. The dried gel was exposed to phosphoimager screen by keeping in phosphoimager cassette overnight

A binding reaction mixture was prepared by adding the following components to a microcentrifuge tube on ic

Binding reaction

The reaction was carried out by incubating at 37⁰C for 30 min. The reaction was stopped by adding 2μl of 0.5M EDTA, pH 8.0 and keeping on ice. A spin column was prepared using 1ml syringe and packed with sterile Sephadex G50 slurry and reaction mixture is applied on the top. The eluate is collected in different microcentrifuge tubes and radioactivity was counted using Geiger counter. The tube showing 7 to 9X106was used for experiment. The column containing the unincorporated [γ-32P] ATP was discarded in radioactive waste bin. The radiolabelled oligonucleotides were annealed with their corresponding complementary unlabelled oligonucleotides. A 50 fold molar excess of the latter was used for annealing for conversion of labelled single strand to double strand. Thetubes were kept in boiling waterbath for 3 min followed by room temperature for 30 min. The tubes were transferred to ice and the oligonucleotides were diluted to 4fmoles/μl using sterile H2O

The oligonucleotides were labelled at their 5'end with 32P using T4 polynucleotide kinase (T4 PNK) enzyme in a reaction given belo

end labelling of the oligonucleotides

Electrophoretic mobility shift assay

Adherent cells growing either on cover slips or chamber slides were fixed with 4% paraformaldehyde for 10 min at room temperature. The cells were washed with PBS thrice for 5 min each and blocking was done in 2% BSA(preparedin PBScontaining 0.3% Triton-X 100) for 1h.The cells were incubatedwith primary antibody(dilutedin PBScontaining 0.3% Triton-X 100)for 2h at room temperature or overnight at 4⁰C.The cells were washed with PBS thrice for 5 min each followed by incubation withAlexa Fluor 488-or 594-conjugatedsecondary (anti-mouse/rabbit) antibodiesfor 1h. Then the cells were mounted on microscopicslides using Vectashieldmountingmediumcontaining nuclear dye DAPI. Imaging was done byeither the laser scanning confocal LSM510 or LSM 750 (Carl Zeiss, Oberkochen, Germany) or fluorescence inverted (Olympus 1X51, Tokyo, Japan) microscope

Immunofluorescence Microscopy

Equal amount of proteins were loadedon an appropriate percentageof denaturing SDS-PAGE gel. After completion ofthe run, the gel was over laid on a PVDF membranecut to the size of gel and sandwiched between filter paper sheets and kept inthe blotting cassette in the presence of transferbuffer. Finally the cassette was put in themini transblotapparatus and blotting was done for 2-3hours at a constantvoltage of 80Vat 4⁰C. For blocking the nonspecific sitesmembrane was incubated with blocking solution(5% non-fat milk solution in TBST)with gentle shaking for 1 hourat room temperature. Excess milk from the membrane was washedoff with TBST and themembrane was incubatedwith primary antibody diluted in 1XTBST for 3 hours atroom temperature or overnight at 4°C withshaking. After incubation the membrane was washedwith TBST and incubatedwithappropriate secondary antibody (conjugated with horse-radish peroxidase)diluted in5% fat free milk solution (in TBST) for 1hat room temperature.The blotwas later washed thricefor 10min eachwith TBST and processed for the detection of proteinsignal using ECL-prime chemiluminescencedetection reagent followed by detectionof signal either on X-ray filmor in a chemiluminescence detectionsystem(Proteinsimple, California, USA)

Immunoblotting

BCA (Bicinchoninic acid) method was used to determine the proteinconcentrationin various samples. The Cu2+ions from cupric sulphate (present inBCA reagent B) reagent arereduced to Cu+by the protein in an alkaline medium. The cuprous ion (Cu+) then combines with BCA (present in BCA reagent A) to give a purple colour whose intensity is proportional to the amount of protein present in the samples. This intensity is measuredby colorimetry at 562 nm. BCA reagent was prepared by mixing reagent A with reagent B in avolumeratio of 50:1. A standard curve was generated using increasing concentrations of BSA (2-10μg) in a 25μl reaction, in a 96 well plate. Cell lysates were also dilutedto same volume in parallel wells. 200μl of BCA reagent was then added to each well and incubated at 370C for 30 minutes. The absorbance readings were then takenin a spectrophotometer at 562 nm. Total protein was quantified by calculation of the slopes of regression lines ofabsorbanceand BSA standards

Protein estimation

For preparation ofcellular homogenate from adherent cell culture, the medium was first removed and cells were washed with ice cold 1X PBS. The cells were then scraped in 1X PBS and pellet down by gentle centrifugation (4000 rpm for 2 minutes) at 40C. Cell lysis buffer was then added to the cell pellets and lysis was allowed for 30 minutes on a rotor at 4⁰C. Post lysis, cellswere centrifuged at 13000 rpm for 10min at 4°C. The pellet was discarded and supernatantwascollectedas cell homogenate

Extraction of total cellular protein

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

Cells were seeded in replicates of five @ 3X103cells per wellinfive different 96well cell culture platesand grown in complete media. The method described earlier was slightly modified and followed (Gillies et al., 1986). After every 24h of seeding, one plate was stained with 0.2% crystal violet in 2% ethanolfor 15 minutestill 4thday i.e. 96h.One plate was stained just after the cells get attached to use as 0h time point. Excess dye was removed from the plates by washing with ample amount of water. Crystal violet dye incorporated in the cells was extracted using 0.1% SDS solution by shaking for 10 minutes on a shaker. Absorbance of the extracted dye was then determined at 570 nm in a spectrophotometer. The experiment was repeated at least three times and the average absorbance was plotted for each time point to generate a growth curve

Cell growth Assay

Table2.2: Cell types used in the present study

In the present thesis, various cell types were used for which the details are provided in the Table 2.2. SiHa, HeLa, HaCaT, U2OS, SaOs , A549,HPLD andHEK-293cells were grown in Dulbecco’s modified Eagle’s medium (HyClone, Thermo Scientific, Logan, Utah, USA) supplemented with 2 mM glutamine (Gibco BRL), 100 U/ml penicillin and streptomycin (Gibco BRL, Carlsbad, CA, USA), and 10% fetal bovineserum (Gibco BRL, Carlsbad, CA, USA) under humified conditions at 37°C and 5% CO2.Cells were grown in cell culture dishes till they attained 70% confluency. For sub culturing, these were then trypsinised using 0.05% Trypsin EDTA solution and incubated for 5 minutes at 370C for cells to be detached from surface. The detached cells were then collected by gentle tapping the dish and pipetting. Trypsin was then inactivated by addition of FBS containing culture medium, transferred to a 15 ml tube and centrifuged at 1500 rpm for 2 minutes in a hanging bucket centrifuge. The cell pellet was then resuspended in complete medium and counted in Neubauercell counting chamber. Viability of the cells was checked by trypan blue exclusion method.Appropriate number of cells wasthen sub cultured in fresh cell culture dishes with culture medium as per the experimental requirements

Maintenance of cell lines

Cell biology methods

Cell lysis Buffer

Fixative

TAE

Resuspension solution(Solution I)

Polydeoxy (Inosinate-cytidylate) (Poly dI-dC)

Cytoplasmic extractionbuffer (without protease inhibitors)

Fixative : 4% Formaldehyde

Cell lysis buffer(RIPA Buffer)

Phosphate Buffered Saline (PBS)

Ammonium persulfate(APS)

Acrylamide (29:1)

Phenylmethylsulfonyl fluoride (PMSF)

Benzamidine

Aprotinin

Leupeptin

NP-40ComponentsFinal concentrationFor 10 mlNP-4010%1mlH2O9ml

Dithiothreitol (DTT)ComponentsFinal concentrationFor 5 mlDTT1.0M0.7725gH2Oq.s

Ethylenediamine tetraacetic acid (EDTA), pH 8.0ComponentsFinal concentrationFor 500 mlEDTA0.5M93.05gH2Oq.sThe pH is adjusted to 8.0 using 10M NaOH

Ethylene Glycol Tetraacetic acid (EGTA), pH 7.0ComponentsFinal concentrationFor 50 mlEGTA0.1M1.902gH2Oq.sThe pH is adjusted to 7.0 using 10M NaOH

Potassium Chloride (KCl)ComponentsFinal concentrationFor 100 mlKCl2M14.91gH2Oq.s

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

Potassium Chloride (KCl)

HEPES pH 7.9ComponentsFinal concentrationFor 100 mlHEPES1M23.83gH2Oq.sThe pH wasadjusted to 7.9 using 10M NaOH

Stock solution

forpreparation ofregular buffers and solutions viz. Tris, Glycine, SDS, Sodium Chloride, Potassium Chloride, Disodium Phosphate,NP-40, Tween 20, TritonX100, Formaldehyde, Glycerol, Agarose, Acrylamide,Bis-Acrylamide,Ammonium per sulphate (APS), TEMED,BSA, Propidium Iodide, RNase Aetc. were obtained from Sigma(St Louis, MO, USA). PVDF membrane, X –ray films and western blotting detection reagent (ECL prime) were obtained from GE Healthcare (Little Chalfont, UK). Proteaseinhibitor tablets were obtained from Roche (Penzberg,Germany). Anti mouse and anti-rabbit secondary antibodies tagged to HRP (Horse radish peroxidise) were obtained from Bangalore Genei(Peenya, India). Secondary antibodies for Immunofluorescence (anti mouseIgGand anti rabbitIgG) conjugated to Alexa Fluor (488 and 594) from Molecular Probes, Invitrogen and Vectashield mounting medium with DAPI wasobtained from vector laboratories(Burlingame, CA, U.S.A).Antibodies from different sources were used in the present study. The list of different antibodies used in the present thesis is provided in Table 2.1.Table 2.1: List of antibodies used

Media for cell culture (DMEM and Ham’s F12) and foetal bovine serum (FBS) were obtained from Gibco, Invitrogen (Carlsbad, CA, USA). Cell culturereagents such asTrypsin, Phosphate Bufferedsaline (PBS), Antibiotics, Glutamine, etc. were also obtained from Gibco, Invitrogen (Carlsbad, CA, USA). Chemicals for cell culture experiments Aphidicholin, Nocadazole, Polybrene, and Puromycinwere obtained from Sigma (St Louis, MO, USA). Cyclosporine A, MTT (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide), wortmannin, UO126, SP 600125, cycloheximide, camptothecin, Tacrolimus/FK506 , Tween 20 and Malachite green were obtained from Sigma-Aldrich (St. Louis, MO, USA). Specific calcineurin substrate RII peptide, calmodulin, eIF-2α inhibitor salubrinal, MG-132 and caspase inhibitor z-VAD FMK were obtained from Calbiochem (San Diego, CA, USA). Cytotoxicity detection kit (LDH) was obtained from Roche Diagnostics, (Mannheim, Germany).Live /Dead cytotoxicity assay kit was obtained from Molecular probes, Life technologies, USA.Lipofectamine-2000 and Opti-MEM for transient transfections were also obtained from Invitrogen(Carlsbad, CA, USA).Growth media for bacteria (LB) was obtained from HiMedia laboratories (Mumbai,India). Enzymes used for recombinant DNA experiments (Restriction endonucleases, DNA ligase) were obtained from New England Biolabs (Ipswich, MA, USA). Markers for DNA and protein gels were from Fermentas (Vilnius, Lithuania). Various kits used for macromolecular isolation (Plasmid isolation kit-Mini and midi, Gel extraction kit, PCR purification kit, RNA isolation kit) were procured from Qiagen(Hilden, Germany) or HiMedia (India).Trizol reagent for RNA isolation was obtained from Invitrogen (Carlsbad, CA, USA). BCA protein estimation kit was from Pierce (Rockford Illinois, USA). Cell fractionation kit was obtained from Fermentas (USA). Kitfor TUNEL assay kit wasobtained from Invitrogen(Carlsbad, CA, USA). PCR reagents (PCR buffer, dNTPs, MgCl2, Taq DNA polymerase) were obtained from Fermentas. Polymerasefor long PCRs (AccuTaq) was obtained from Sigma. Reverse transcriptase (SuperScript III) was obtained from Invitrogen. Various chemicals required

Media, reagents, chemicals and antibodies

Maintenance of cell lines

Inpresent thesis, various cell lines have been used as mentionedearlier. Cells were either cultured in DMEM or RPMI medium containing 10% fetal bovine serum (FBS)along with antibiotics such as penicillin (100 U/ml), and streptomycin (100 μg/ml).In general, cells were grownin tissue culture T-75 flaskupto 85-90% confluency. Cells are washedwith PBS, followed by trypsinization with 0.05% Trypsin EDTA solution. Cells were detachedfrom the surfaceeither by gentle tapping or gentlepipettingor incubated for 5 minutes at 37°C. Culture medium containing serum was then added to inactivate trypsin. After careful mixing, cells were transferred to a 15 ml tube and centrifuged at 800 rpm for 5minutes. The cell pellet wasre-suspended in a fresh culture media containing FBS. The cell viability was checked by trypan blue staining, followed bycounting in Neubauer cell-counting chamber. Appropriate number of cells wasthen either sub-culturedin the ratio of 1:4 to 1:6or seeded in culture dishes as per the experimental requirements.Cells were maintained in humidified incubator at 37ºC in 5% CO2-95% air, throughout the experiment

Extraction buffer

MTT reagent

For Cytotoxicity assays

6XEMSA sample loading dye

5X EMSA buffer

Native EMSA PAGE

10XBinding buffer

For Electrophoretic Mobility Shift Assay (EMSA)

For preparation of Ultra competent cells

Inoue buffer

6X DNA loading dye

Agarose gel

TAE

For DNA electrophoresis

Nuclear lysis buffer (without protease inhibitors

Cytoplasmic extraction buffer (without protease inhibitors)

For Cell fractionation

Blocking buffer: 2% BSA

Permeabilisation buffer: 0.2% Triton X100

4% Formaldehyde fixative

For Immunofluorescence(IF)

Stripping buffer

Blocking buffer

TBS-T

Transfer buffer

(f) Running buffer

(e) Stacking polyacrylamide gel

(d) Resolvingpolyacrylamide gel

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

(b) Celllysis buffer B(For IB)

Cell lysis bufferA(For IP)

II. For Immunoprecipitation(IP)and Immunoblotting(IB)

Table 2.1: Commonly used buffers and solutionsI. General buffers(a)Phosphate Buffered Saline (PBS)

The following antibodies were used in the present study:Primary antibodies against GAPDH (anti-rabbit), FLAG (anti-mouse), Immunoglobulin (IgG, anti-rabbit or anti-mouse),profilin-1 (anti-rabbit), tubulin (anti-mouse) and ubiquitin (anti-rabbit) were obtained from Sigma Aldrich Chemicals(St Louis, MO, USA). Antibodies againstAKT (anti-rabbit), cleaved caspases-3, 8 and 9 (anti-rabbit),HA-tag(anti-rabbit), Myc-tag (anti-rabbit), p21 (anti-rabbit), phospho-p53 (anti-mouse), PTEN (anti-mouse), phospho-AKT (Ser473; anti-rabbit), phospho-GSK-3β (Ser9; anti-rabbit), phospho-IKKα/β (Ser177/181; anti-rabbit), phospho-IκBα (Ser32; anti-rabbit), and phospho-p65 (Ser276; anti-rabbit) were obtained from Cell Signaling Technologies(Danvers, MA, USA), whereas antibodies for cox-2 (anti rabbit), c-Rel (anti-rabbit), ICAM-1 (anti-rabbit), IKKα/β (anti rabbit), IκBα (anti-rabbit), Mdm2 (anti-rabbit), PARP-1/2 (anti-rabbit), Rel-B (anti-rabbit), p50 (anti-rabbit), p53 (anti-mouse), p65 (anti-rabbit) were obtained from Santa Cruz Biotechnology(Santa Cruz, CA, USA).HRP (Horse radish peroxidase)-conjugated secondary antibodies (anti mouse and anti-rabbit) were obtained from Bangalore Genie(Peenya, India). For immuno-fluorescencestudies, secondary antibodiesconjugated toAlexa Fluor (488 and 594, anti-mouse and anti-rabbit) were obtained from Molecular Probes, Invitrogen(Eugene, OR, USA)

Antibodies

S. cerevisiae strains were routinely grown either in rich YPD mediumorsyntheticcomplete medium (SC)(Section 2.1.5.1) at 30°C with continuous shaking at 200 rpm unless otherwise stated. In general, S. cerevisiae frozen glycerol stocks were revived on 2% YPD medium by streaking and allowed to grow for 1-2 days. S. cerevisiae strains harbouringaplasmid containingthe URA3geneas the auxotrophy selectionmarker were revived on synthetic complete medium lacking uracil (SC-Ura).To prepare liquid cell culture, a single colony of each S. cerevisiae strain was inoculated either in YPD or SC-Ura medium and grown for 14-16 h. S. cerevisiae strains streaked on plates were sealed with paraffin film (parafilm M) and stored at 4°C for a maximum period of 2 weeks.Protein over expression in yeast was carried in presence of galactose instead of glucose as the carbon source, as the plasmid pYesGex 6p2 carries the GALpromoter under which yeast proteins were expressed

Strains and culture conditions

20 mM HEPES pH 6.8100 mM NaCl2 mM EDTA5 mM DTTYeast protease inhibitor cocktail and phosphatase inhibitor cocktail (added fresh to the buffer A)

Buffer A

EDTA (pH 8.0)186.1 g of EDTA.2H2O was dissolved into 800 mL of water stirredvigorously and the pH was adjusted with NaOH pellets. When the pH of the solution reached8.0 EDTA dissolvedcompletely and was made upto 1000 mL with water.Tris-HCl buffer (1M)121.1 g of Tris base was dissolved in 800 mLof water and pH was adjusted to 7.2 using concentrated HCl Tris-EDTA (TE) buffer 10 mM Tris-HCl, pH 8.01 mM EDTA Tris-Acetic acid EDTA (TAE) buffer 40 mM Tris base 1mMEDTApH was adjusted to 8.4with glacial acetic acid. TAE buffer was prepared as a 50X stock solution and used at 1Xconcentration.Tris-Saline20 mM Tris-HCl, pH 7.20.9% NaCl

PhosphateBuffered Saline (PBS) 137 mM NaCl 2.7 mM KCl 10 mM Na2HPO42 mM KH2PO4pH was adjusted to 7.3 using HCl and NaOH beforeautoclaving. PBS was prepared as a 10X stock solution and diluted to 1X concentration before autoclaving

Common buffers

Yeast synthetic complete medium without leucine(SC-Leu)0.67% Yeast Nitrogen Base without amino acids 76mg/L His76mg/L Ura76 mg/mL Trp76 mg/mL Met2% DextroseYeast sporulating medium1% Potassium acetate0.05% Dextrose

Yeast extract Peptone Dextrose (YPD)1% Yeast extract2% Peptone 2% Dextrose Yeast synthetic complete medium(SC)0.67% Yeast Nitrogen Base with amino acids 2% Dextrose1.92 g/LYeast Synthetic Drop-Out media supplement without Uracil76 mg/L uracilYeast synthetic complete medium without histidine(SC-His)0.67% Yeast Nitrogen Base without amino acids 1.92 g/L Yeast Synthetic Drop-Out media supplement without histidine2% DextroseYeast synthetic complete medium without uracil(SC-Ura)0.67% Yeast Nitrogen Base without amino acids 1.92 g/LYeast Synthetic Drop-Out media supplement without Uracil2% DextroseYeast synthetic complete medium without methionine(SC-Met)0.67% Yeast Nitrogen Base without amino acids 380mg/L Leu76 mg/L His76mg/L Ura2% DextroseYeast synthetic complete medium without tryptophan(SC-Trp)0.67% Yeast Nitrogen Base without amino acids 380mg/L Leu76mg/L His76mg/L Ura76 mg/L Met2% Dextrose

Yeast media(Media composition was followed as described by Sigma product data sheet)

All S. cereviseae and bacterial strains and plasmids used in this study are listed in Table 2.1and 2.2

Strains and plasmids

Cells were plated in a manner that they were 30-50% confluent on the day of transfection.Cells were washed with serum-free medium,and the serum-free medium was added to the cells as per plate size. SiRNA was diluted in the serum-free medium, and oligofectamine was diluted in serum-free media, separately (Table 10). Both the complexes were incubated at room temperature for 5 min. Diluted siRNA wasmixed gently with diluted oligofectamine and incubated at room temperature for 15 min. The final transfection mixture was added dropwise to the cells and mixed properly by gentle rocking. Cells were incubated for 4 hrs.,and the growth medium containing 10% FBS was added to the plates without removing the previous medium. Cells were incubated overnight at 37°C in a CO2 incubator. After overnight incubation, the siRNA transfection was repeated using the same protocol. Cells were harvested after 24-48 hours of second round siRNA transfection. The knockdown was detected bychecking the protein levels throughwestern blotting. (Note: SiRNA transfection is carried out in antibiotic free medium)Table 10: SiRNA transfection methodology

SiRNA

Table 8: Lipofectamine plasmid-transfection methodology

For transfection with Lipofectamine, cells were plated in antibiotic-free medium 24 h before transfection and were transfected at a confluency of 70-80% as per the manufacturer’s protocol. The plasmid of interest was incubated in serum free media,and Lipofectaminewas incubated in serum free media forseparately5minutes. The plasmid and the Lipofectamine mixtures(Table 8)were mixedgentlyand incubated at room temperature for 20 min.;thetransfection mixture was added dropwise to the cells. Transfection media was replaced with the fresh complete medium after 6 hrs.of transfection and cell are harvested after 24 hours

Plasmid transfection using Lipofectamine 2000

Amplified PCR products were run on Agarose gel to check for the amplification ofgene of interests

PCR amplification of the gene of interests was carried out by following the method mentioned in table 4.Table 4: PCR methodology

Polymerase chain reaction (PCR)

The following chemicalswere used in the present study: Ampicillin, EDTA (USB), dNTPs, Taq DNA polymerase(Fermentas), Pfu DNA polymerase (Stratagene), DpnI (New England Biolabs), Plasmid miniprep, midiprep, and maxiprepkits(Qiagen, and Invitrogen), glycine, EGTA, NaCl, Tris (Fisher Scientific), NH4Cl, acrylamide(SRL), Cisplatin, Doxorubicin, MG132,Cadmium chloride,Nonident P-40, propidium iodide (PI),bis-acrylamide, SDS, TEMED, Ammonium persulphate (APS), CoomassieBrilliant Blue, DAPI, IPTG, kanamycin, Aprotinin, pepstatin, PMSF, -Glycerophosphate, Sodium Fluoride (NaF),Biotin, and DMSO(Sigma), Luciferase assay kit (Promega#1500), Gateway cloning kit, DMEM, FBS, RPMI, Opti-MEM medium,Met-/Cys-DMEM, dialyzed FBS,trypsin-EDTA, L-glutamine, PBS, Lipofectamine 2000, Oligofectamine, (Invitrogen), PEI(Polysciences), milkpowder (Warana), protein G agarose beads, Streptavidin sepharose beads, Glutathionesepharose beads, MBP beads (GE Healthcare), S-protein beads (Novagen/Calbiochem), HA beads(Covance), LB media(Himedia)

Chemicals and reagents

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

200 rpm in LBbroth supplemented with appropriate antibiotics (plasmid antibiotic marker). Cells were harvested by centrifugation at 12,000 g for 5 min. Plasmids were extracted using Qiagen plasmid miniprep ormidiprep kit following the manufacturer’s instructions. Concentration of the extracted plasmid DNAs was measured using spectrophotometer at 280 nm and stored at -20°C

E.colistrains carrying plasmids were inoculated and grown overnight at 37°C and

Plasmid DNA purification

A microtipful cells of bacterial strain from appropriate medium was resuspended in 20 μl sterile water and incubated at 98°C for 10 min for cell lysis. 2 μl of heat-lysed cell suspension was used as template in 25 μl PCR reaction

Xanthomonasand E.colicolony PCR

and finally resuspended in 100 μl sterile water. Bacterial cell suspension was aliquoted in 20 μl volume. The above procedure was followed for all the three strains and cell suspension of three different strains were mixed together in 1:1:1 ratio. For conjugation to occur, 20 μl of the above mixture was spottedon the LB agar plate and incubated at 37°C for 12-16 h. Next, the conjugation drops were streaked on LB agar plate containing appropriate antibiotics to select the S17-1 recipient containing recombinant plasmid.S17-1 was directly conjugated with Xanthomonasstrain. S17-1 strain containing recombinant plasmid (3 ml) and recipient Xanthomonasstrain (100 ml) was grown overnight with appropriate antibiotics. Cells were harvested and washed thrice as mentioned earlier. Xanthomonasstrain was finally dissolvedin 600-700 μl sterile water and S17-1 strain was dissolved in 3 ml sterile water. 50 μl Xanthomonascell suspension and 10 μl S17-1 cell suspension were mixed together and 20 μl was spotted on PS agar plate. After 40 h of incubation at 28°C, each conjugation drop was dissolved in 400 μl water separately and plated on PS agar medium with rifampicin (counter-selectable marker) and plasmid specific antibiotics for specific selection of Xanthomonascolony with recombinant plasmid

Since compatible conjugation does not exist between Xanthomonasand E.coliDH5α strain.Therefore, upon getting the appropriate clones in DH5α, conjugation was performed with S17-1 (recipient strain) and PRK600 (helper strain). All the three strains (DH5α with clone, S17-1 and PRK600 strain of E.coli) were grown overnight at 37°C with constant shaking at 200 rpm in 3 ml LB broth. Cells from 1 ml overnight grown cultures were harvested by centrifugation followed by three washes with s

Xanthomonas conjugation

shaking at 200 rpm. 1% of overnight grown culture was inoculated in 100 ml fresh PS medium and grown to obtain log-phase culture. Log phase Xanthomonas culture was kept on ice for 10-15 min, aliquoted in 50 ml pre-chilled centrifuge tubes and centrifuged at 4000-5000 g at 4°C for 10 min. Supernatant was discarded and pellet from each tube was gently resuspended in 10-20 ml sterile chilled water. Next, cells were harvested by centrifugation at 4000 g at 4°C for 10 min and supernatant was discarded. Harvested cells were washed twice and finally resuspended in adequate amount of prechilled sterile water. 100 μl of cell suspension was aliquoted in sterile 1.5 ml microcentrifuge tubes and kept on ice. For transformation, Xanthomonaselectrocompetent cells and appropriate amount of plasmid DNA was mixed, and kept on ice in laminar hood. This mixture was added to 1 mm electroporation cuvettes (Biorad) and tapped gently to allow the cells to settle properly in order to avoid air bubbles. Competent cells were electroporated (1800 V, 25 μF, 200 Ω, 1mm cuvette) followed by immediate addition of fresh PS broth in the cuvette, mixed properly and taken in the microcentrifuge tubes. Microcentrifuge tubes containing transformed cells were incubated at 28°C for 2 hours with continuous shaking for recovery. After recovery, cells were plated on specific medium with appropriate antibiotics and incubated in 28°C plate incubator

For electrocompetent cell preparation, single colony of desired Xanthomonasstrain was inoculated in 5 ml PS medium and grown overnight at 28°C

Xanthomonastransformation

E.coliDH5α strain was transformed with plasmids carrying appropriate inserts to generate clones, and Xanthomonas deletion strains. Ultracompetent cells stored at -80°C were thawed on ice for 5-10 min. 5 μl ligated plasmid was added to 100 μl ultracompetent cells and incubated on ice for 30 min. Next, competent cells were subjected to heat shock at 42°C for 90 seconds. Cells were immediately transferred on ice for 2-3 min. Next, 1 ml LB medium was added and cells were allowed to recover for 1 h on a shaker incubator set at 37°C. After the recovery, cells were centrifuged at 3000 g for 3 min. Medium supernatant was discarded and cells were resuspended in 100 μl fresh sterile medium. Cells were plated on LB agar containing appropriate antibiotics. Plates were incubated at 37°C for 12-16 h

E.colitransformation

A single colony of E.coliDH5α strain was inoculated in 5 ml LB medium and incubated at 37°C for overnight. 1% of overnight grown culture was inoculated in 500 mlfresh LB medium and incubated at 37°C for 2-3 h till the OD600 reached to 0.4-0.5. Culture was chilled on ice for 5 min followed by centrifugation at 3000 g for 15 min at 4°C. Harvested cells were washed gently with 200 ml ice-cold TFb-I buffer. Cells were collected by centrifugation at 3000 g for 5 min at 4°C and gently resuspended in 20 ml ice-cold TFb-II buffer. Bacterial cell suspension was kept on ice for 15 min and was aliquoted in 100 μl volumes in chilled sterile microcentrifuge tubes. Cells were immediately snap-frozen in liquid nitrogen and stored at -80°C

Preparation of E.coliultracompetent cells