PMID:22130678

Citation	Liu, H, Gu, D, Cao, X, Liu, Q, Wang, Q and Zhang, Y (2012) Characterization of a new quorum sensing regulator luxT and its roles in the extracellular protease production, motility, and virulence in fish pathogen Vibrio alginolyticus. Arch. Microbiol. 194:439-52
Abstract	Vibrio alginolyticus, an opportunistic pathogen that causes vibriosis in miscellaneous fish species, has brought about serious economic damage to the mariculture industry in South China. The mechanism of virulence regulation in V. alginolyticus is yet not known except a Vibrio harveyi-like quorum sensing (QS) system that is established to manipulate the expression of diverse genes including those encoding virulence determinants. In this study, a new TetR family QS regulator, luxT, was identified and characterized in V. alginolyticus. The transcription of luxT gene was cell density dependent and was positively regulated by LuxU, an established QS component relaying the signal from three paralleled QS regulatory systems in V. harveyi. In addition, luxT positively regulated both luxO at transcriptional level and luxR at post-transcriptional level, which is thoroughly different from the established QS regulation mode in V. harveyi and Vibrio vulnificus. The mutant of luxT deletion produced markedly decreased total extracellular proteases and reduced motility ability compared to the wild type and the complemented strain luxT (+). The fish infection results indicated that mutation of luxT led to marginal attenuation in the virulence of V. alginolyticus, suggesting that LuxT might play a role in the fine-tuning of the virulence via QS in V. alginolyticus.
Links	PubMed Online version:10.1007/s00203-011-0774-x
Keywords	Animals; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Cloning, Molecular; Fish Diseases/microbiology; Gene Expression Regulation, Bacterial; Genes, Regulator; Molecular Sequence Data; Peptide Hydrolases/metabolism; Quorum Sensing/genetics; Sequence Deletion; Transcription, Genetic; Vibrio Infections/microbiology; Vibrio Infections/veterinary; Vibrio alginolyticus/genetics; Vibrio alginolyticus/pathogenicity; Vibrio alginolyticus/physiology; Virulence/genetics; Zebrafish/microbiology
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
VIBAL:D0WWP7		GO:0007165: signal transduction	ECO:0000315:		P		Figure 2	complete CACAO 9671
VIBAL:D0WWP7	involved_in	GO:2000147: positive regulation of cell motility	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete
VIBAL:D0WWP7	involved_in	GO:0007165: signal transduction	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete
VIBAL:D0WWP7	involved_in	GO:1902573: positive regulation of serine-type peptidase activity	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete
VIBAL:D0WWP7		GO:2000147: positive regulation of cell motility	ECO:0000315:		P		Fig 3: Uses agar colony growth as well as qRT-PCR descriptions of the amount of lafK, a swarming regulator gene, to shows that in comparison with cells expressing LuxT, those with the gene knocked out have decreased swarming ability and general motility.	complete CACAO 9672
VIBAL:D0WWP7		GO:1902573: positive regulation of serine-type peptidase activity	ECO:0000315:		P		Figure 3a: Shows that LuxT positively regulates the productions of extracellular protease (characterized endotoxins). This was detected using gene mutants and a HPA coloration assay to detect the extracellular protease levels. Figure 3b: Includes a western blot that shows extracellular protease production is markedly decreased in a LuxT knockout. These results indicate that LuxT positively regulated extracellular protease production which further indicates that LuxT regulates endotoxin activity.	complete CACAO 9673

References

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