Chitin degradation and its effect on natural transformation: a systematic genetic study in Vibrio parahaemolyticus.

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Date: Aug. 2022
From: Canadian Journal of Microbiology(Vol. 68, Issue 8)
Publisher: NRC Research Press
Document Type: Report
Length: 5,646 words
Lexile Measure: 1350L

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Abstract :

The degradation of polymeric chitin by chitinase liberates soluble N-acetyl glucosamine oligosaccharides ([GlcNAc.sub.n [greater than or equal to] 2]), a source of nutrition that can also induce a state of natural genetic competence in Vibrio parahaemolyticus. This analysis revealed that among seven predicted chitinases, the synergistic action of VPA0055 (ChiA2), VP0619 (ChiB), and VPA0832 (Cdx) were essential for the robust growth and high transformation frequency on chitin. The endochitinase, ChiA2, and periplasmic chitinase, Cdx were indispensable for chitin degradation. ChiB was not essential for growth on chitin but did have an effect on the rate of chitin degradation. Interestingly, the loss of Cdx drastically reduced growth on insoluble chitin, but growth on soluble [GlcNAc.sub.5/6] remained same. The utilization of [GlcNAc.sub.5/6] was only inhibited when there was mutation of Cdx with the other periplasmic chitinases VP0755 and VP2486. This suggests that Cdx might also be involved in extracellular degradation of chitin, in addition to its role as a periplasmic chitinase. Moreover, the periplasmic chitin oligosaccharide-binding protein (CBP) was found to be essential for the efficient utilization of chitin. The CBP was specifically needed for the processing of [GlcNAc.sub.4-6] during growth on chitin. Overall, this study provides detailed analysis of the machinery behind chitin degradation in V. parahaemolyticus. Key words: chitin, chitinase, [GlcNAc.sub.6], ChiA2, chitodextrinase, chitoporin La degradation d'un polymere de chitine par la chitinase libere des oligosaccharides solubles de N-acetyl glucosamine ([GlcNAc.sub.n [greater than or equal to] 2]), une source nutritive qui peut egalement induire un etat de competence genetique naturelle chez Vibrio parahaemolyticus. Cette analyse a revele que parmi les 7 chitinases predites, l'action synergique de VPA0055 (ChiA2), VP0619 (ChiB) et VPA0832 (Cdx) etait essentielle pour la croissance robuste et la frequence de transformation elevee sur la chitine. L'endochitinase, ChiA2 et la chitinase periplasmique, Cdx etaient indispensables pour la degradation de la chitine. ChiB n'etait pas essentielle pour la croissance sur la chitine, mais avait un effet sur le taux de degradation de la chitine. Il est interessant de noter que la perte de Cdx reduisait considerablement la croissance sur la chitine insoluble, mais la croissance sur la [GlcNAc.sub.5/6] soluble restait la meme. L'utilisation de la [GlcNAc.sub.5/6] n'etait inhibee qu'en cas de mutation de Cdx avec les autres chitinases periplasmiques VP0755 et VP2486. Ceci suggere que Cdx pourrait egalement etre impliquee dans la degradation extracellulaire de la chitine, en plus de son role de chitinase periplasmique. En outre, la proteine periplasmique CBP (chitin oligosaccharide binding protein) s'averait essentielle pour l'utilisation efficace de la chitine. La CBP etait specifiquement requise pour le traitement de la [GlcNAc.sub.4-6] pendant la croissance sur la chitine. Dans l'ensemble, cette etude fournit une analyse detaillee des mecanismes de degradation de la chitine chez V. parahaemolyticus. [Traduit par la Redaction] Mots-cles: chitine, chitinase, [GlcNAc.sub.6], ChiA2, chitodextrinase, chitoporine

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Gale Document Number: GALE|A715418814