title: Quorum sensing positively regulates flagellar motility in pathogenic Vibrio harveyi.
abstract: Vibrios belonging to the Harveyi clade are among the major pathogens of aquatic organisms. Quorum sensing (QS) is essential for virulence of V. harveyi towards different hosts. However, most virulence factors reported to be controlled by QS to date are negatively regulated by QS, therefore suggesting that their impact on virulence is limited. In this study, we report that QS positively regulates flagellar motility. We found that autoinducer synthase mutants showed significantly lower swimming motility than the wild type, and the swimming motility could be restored by adding synthetic signal molecules. Further, motility of a luxO mutant with inactive QS (LuxO D47E) was significantly lower than that of the wild type and of a luxO mutant with constitutively maximal QS activity (LuxO D47A). Furthermore, we found that the expression of flagellar genes (both early, middle and late genes) was significantly lower in the luxO mutant with inactive QS when compared with wild type and the luxO mutant with maximal QS activity. Motility assays and gene expression also revealed the involvement of the quorum-sensing master regulator LuxR in the QS regulation of motility. Finally, the motility inhibitor phenamil significantly decreased the virulence of V. harveyi towards gnotobiotic brine shrimp larvae.
authors: Laboratory of Aquaculture & Artemia Reference Center, Ghent University, Ghent, Belgium.
authors: Qian
authors: Q
authors: Yang
authors: Tom
authors: T
authors: Defoirdt
mesh_terms: D000584:Amiloride / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D059001:Aquatic Organisms / Q000235:genetics / Q000378:metabolism; D001156:Artemia / Q000382:microbiology; D001426:Bacterial Proteins / Q000235:genetics*; D005407:Flagella / Q000235:genetics* / Q000378:metabolism; D053038:Quorum Sensing / Q000235:genetics / Q000502:physiology*; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D015222:Sodium Channels / Q000187:drug effects; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics*; D014733:Vibrio / Q000235:genetics / Q000472:pathogenicity*; D037521:Virulence Factors / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; C085427:LuxI protein, Bacteria; C088907:LuxO protein, Vibrio harveyi; D012097:Repressor Proteins; D015222:Sodium Channels; D015534:Trans-Activators; D014157:Transcription Factors; D037521:Virulence Factors; C064778:LuxR autoinducer binding proteins; C047088:phenylamil; D000584:Amiloride