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Debnath, Anusuya Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University
Mizuno, Tamaki Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University researchmap
Miyoshi, Shin-Ichi Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University
Abstract
Vibrios can degrade chitin surfaces to soluble N-acetyl glucosamine oligosaccharides (GlcNAc(n)) that can be utilized as a carbon source and also induce a state of natural genetic competence. In this study, we characterized chitin-dependent growth and natural competence in Vibrio parahaemolyticus and its regulation. We found that growth on chitin was regulated through chitin sensors ChiS (sensor histidine kinase) and TfoS (transmembrane transcriptional regulator) by predominantly controlling the expression of chitinase VPA0055 (ChiA2) in a TfoX-dependent manner. The reduced growth of Delta chiA2, Delta chiS and Delta tfoS mutants highlighted the critical role played by ChiA2 in chitin breakdown. This growth defect of Delta chiA2 mutant could be recovered when chitin oligosaccharides GlcNAc(2) or GlcNAc(6) were supplied instead of chitin. The Delta tfoS mutant was also able to grow on GlcNAc(2) but the Delta chiS mutant could not, which indicates that GlcNAc(2) catabolic operon is dependent on ChiS and independent of TfoS. However, the Delta tfoS mutant was unable to utilize GlcNAc(6) because the periplasmic enzymes required for the breakdown of GlcNAc(6) were found to be downregulated at the mRNA level. We also showed that natural competence can be induced only by GlcNAc(6), not GlcNAc(2), because the expression of competence genes was significantly higher in the presence of GlcNAc(6) compared to GlcNAc(2). Moreover, this might be an indication that GlcNAc(2) and GlcNAc(6) were detected by different receptors. Therefore, we speculate that GlcNAc(2)-dependent activation of ChiS and GlcNAc(6)-dependent activation of TfoS might be crucial for the induction of natural competence in V. parahaemolyticus through the upregulation of the master competence regulator TfoX.
Keywords
chitin
chitinase
GlcNAc(6)
natural competence
ChiA2
ChiS
TfoS
Published Date
2020-08-26
Publication Title
Microorganisms
Volume
volume8
Issue
issue9
Publisher
MDPI
Start Page
1303
ISSN
2076-2607
Content Type
Journal Article
language
英語
OAI-PMH Set
岡山大学
Copyright Holders
© 2020 by the authors.
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DOI
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Related Url
isVersionOf https://doi.org/10.3390/microorganisms8091303
License
http://creativecommons.org/licenses/by/4.0/
Funder Name
Ministry of Education, Culture, Sports, Science and Technology
助成番号
JP19fm0108002