- Jul 2018
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europepmc.org europepmc.org
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On 2017 Oct 13, Martine Crasnier-Mednansky commented:
The authors really should not write in legend of figure 7, "Our results indicate that for robust growth on chitin, the transporters responsible for uptake of [ABC-transported] chitobiose and [PTS-transported] GlcNAc play the largest role". In fact, data in figure 6A indicate lack of either one of these two transporters does not impair growth on chitin at all. Also, the 'chitosan' PTS (PTS<sup>Chs</sup>, VC1282 in the figure), cannot possibly be a major player considering there is little glucosamine in chitin. Moreover, PTS<sup>Chs</sup> transport is most likely inhibited by Enzyme IIA<sup>Glc</sup>-dependent PTS transports (including PTS<sup>Nag</sup>), as it was reported chs expression is positively regulated by cAMP (Berg T, 2007).
A proper question is whether or not the two transporters can be used simultaneously, as depicted in figure 7. Upon in vitro characterization of the periplasmic chitodextrinase activity (VCA0700 in Vibrio cholerae), Keyhani NO, 1996 proposed the ABC transport at first predominates up to a threshold concentration of (GlcNAc)n, n≥3, above which the PTS transport predominates. The two transport systems are not physiologically redundant.
This comment, imported by Hypothesis from PubMed Commons, is licensed under CC BY.
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- Feb 2018
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europepmc.org europepmc.org
-
On 2017 Oct 13, Martine Crasnier-Mednansky commented:
The authors really should not write in legend of figure 7, "Our results indicate that for robust growth on chitin, the transporters responsible for uptake of [ABC-transported] chitobiose and [PTS-transported] GlcNAc play the largest role". In fact, data in figure 6A indicate lack of either one of these two transporters does not impair growth on chitin at all. Also, the 'chitosan' PTS (PTS<sup>Chs</sup>, VC1282 in the figure), cannot possibly be a major player considering there is little glucosamine in chitin. Moreover, PTS<sup>Chs</sup> transport is most likely inhibited by Enzyme IIA<sup>Glc</sup>-dependent PTS transports (including PTS<sup>Nag</sup>), as it was reported chs expression is positively regulated by cAMP (Berg T, 2007).
A proper question is whether or not the two transporters can be used simultaneously, as depicted in figure 7. Upon in vitro characterization of the periplasmic chitodextrinase activity (VCA0700 in Vibrio cholerae), Keyhani NO, 1996 proposed the ABC transport at first predominates up to a threshold concentration of (GlcNAc)n, n≥3, above which the PTS transport predominates. The two transport systems are not physiologically redundant.
This comment, imported by Hypothesis from PubMed Commons, is licensed under CC BY.
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