LuxS modulates motility and secretion of extracellular protease in fish pathogen Vibrio harveyi.

Citation metadata

From: Canadian Journal of Microbiology(Vol. 68, Issue 3)
Publisher: NRC Research Press
Document Type: Report
Length: 6,749 words
Lexile Measure: 1510L

Document controls

Main content

Abstract :

Vibrio harveyi can cause infections and diseases in a variety of marine vertebrates and invertebrates, which are harmful to the aquaculture industry. The LuxS quorum-sensing system regulates the expression of virulence factors in a wide variety of pathogenic bacteria. In this study, an in-frame deletion of the luxS gene was constructed to reveal the role of LuxS in the physiology and virulence of V. harveyi. Statistical analysis showed no significant differences in the growth ability, biofilm formation, antibiotic susceptibility, virulence by intraperitoneal injection, and ability of V. harveyi to colonize the spleen and liver of the pearl gentian grouper between the wild-type (WT) and luxS mutant. However, deletion of luxS decreased the secretion of extracellular protease, while increasing swimming and swarming abilities. Simultaneously, a luxS-deleted mutant showed overproduction of lateral flagella, and an intact luxS complemented this defect. Since motility is flagella dependent, 16 V. harveyi flagella biogenesis related genes were selected for further analysis. Based on quantitative real-time reverse transcription-PCR (qRT-PCR), the expression levels of these genes, including the polar flagella genes flaB, flhA, flhF, flhB, flhF, fliS, and flrA and the lateral flagella genes flgA, flgB, fliE, fliF, lafA, lafK, and motY, were significantly upregulated in the [DELTA]luxS: pMMB207 ([[DELTA]luxS.sup.+]) strain as compared with the V. harveyi 345: pMMB207 ([WT.sup.+]) and C-[DELTA]luxS strains during the early, mid-exponential, and stationary growth phases. Our results indicate that LuxS plays an important role in controlling motility, flagella biogenesis, and extracellular protease secretion in V. harveyi. Key words: Vibrio harveyi, luxS, motility, flagella, extracellular protease secretion. Vibrio harveyi peut provoquer des infections et des maladies chez une variete de vertebres et d'invertebres marins, ce qui est tres nuisible a l'industrie de l'aquaculture. On rapporte que le systeme de detection du quorum LuxS regule l'expression de facteurs de virulence dans une grande variete de bacteries pathogenes. Dans cette etude, une deletion en phase du gene luxS a ete construite afin de reveler le role de LuxS dans la physiologie et la virulence de V. harveyi. L'analyse statistique n'a montre aucune difference significative dans la capacite de croissance, la formation de biofilms, la sensibilite aux antibiotiques, la virulence par injection intraperitoneale, et la capacite de V. harveyi a coloniser la rate et le foie du merou hybride (merou marron * merou lanceole) entre le type sauvage (WT) et le mutant luxS. Toutefois, la deletion de luxS diminuait la secretion d'une protease extracellulaire tout en augmentant la capacite de nage et d'essaimage. Un mutant depourvu de luxS presentait egalement une surproduction de flagelles lateraux tandis que luxS intact complementait ce defaut. Puisque la motilite depend des flagelles, 16 genes lies a la biogenese des flagelles de V. harveyi ont ete selectionnes pour une analyse plus approfondie. Selon les resultats de la PCR quantitative en temps reel (qRTPCR), les niveaux d'expression de ces genes, y compris les genes des flagelles polaires flaB, flhA, flhF, flhB, flhF, fliS, et flrA et les genes des flagelles lateraux flgA, flgB, fliE, fliF, lafA, lafK, et motY, etaient significativement regules a la hausse chez la souche [DELTA]luxS : pMMB207 ([[DELTA]luxS.sup.+]) par rapport aux souches de V. harveyi 345 : pMMB207 ([WT.sup.+]) et C-[DELTA]luxS au cours de la phase de croissance precoce, mi-exponentielle et stationnaire. Ces resultats indiquent que LuxS joue un role important dans le controle de la motilite, de la biogenese des flagelles et de la secretion de proteases extracellulaires chez V. harveyi. Mots-cles : Vibrio harveyi, luxS, motilite, flagelles, secretion de proteases extracellulaires.

Source Citation

Source Citation   

Gale Document Number: GALE|A696008268