Dataset Information

A variant quorum sensing system in Aeromonas veronii MTCC 3249.

ABSTRACT: We have investigated the quorum sensing control in Aeromonas veronii MTCC 3249, originally isolated as A. culicicola from the midgut of Culex quinquefasciatus. Based on biosensor assays, the bacterium showed constant production of multiple acyl-homoserine lactones (AHLs) with increasing cell-density. The luxRI gene homologs, acuR (A. culicicola transcriptional Regulator) and acuI (A. culicicola autoInducer) were successfully amplified by inverse-PCR. Sequence analysis indicated acuRI were divergent from all known quorum sensing gene homologs in Aeromonas. Two localized regions in the C-terminal autoinducer binding domain of acuR showed indels suggesting variations in autoinducer specificity. Further, only a single copy of the quorum sensing genes was detected, suggesting a tight regulation of mechanisms under its control. Chromatography and further chemical analysis identified two AHLs in the culture supernatant: 6-carboxy-HHL (homoadipyl homoserine lactone), a novel AHL, and N-tetradecanoylhomoserine lactone. The existence of a potentially variant quorum sensing system might therefore, reflect in some way the ecological strategies adopted by this bacterium in the mosquito midgut.

SUBMITTER: Jangid K

PROVIDER: S-EPMC3355384 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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A variant quorum sensing system in Aeromonas veronii MTCC 3249.

Jangid Kamlesh K Parameswaran Perunninakulath S PS Shouche Yogesh S YS

Sensors (Basel, Switzerland) 20120326 4

We have investigated the quorum sensing control in Aeromonas veronii MTCC 3249, originally isolated as A. culicicola from the midgut of Culex quinquefasciatus. Based on biosensor assays, the bacterium showed constant production of multiple acyl-homoserine lactones (AHLs) with increasing cell-density. The luxRI gene homologs, acuR (A. culicicola transcriptional Regulator) and acuI (A. culicicola autoInducer) were successfully amplified by inverse-PCR. Sequence analysis indicated acuRI were diverg ...[more]

PMID: 22666003

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Project description:Our earlier studies showed that AhyRI- (AI-1) and LuxS-based (AI-2) quorum sensing (QS) systems were positive and negative regulators of virulence, respectively, in a diarrheal isolate SSU of Aeromonas hydrophila. Recently, we demonstrated that deletion of the QseBC two-component signal transduction system (AI-3 QS in enterohemorrhagic Escherichia coli) also led to an attenuation of A. hydrophila in a septicemic mouse model of infection, and that interplay exists between AI-1, AI-2, and the second-messenger cyclic-di-guanosine monophosphate (c-di-GMP) in modulating bacterial virulence. To further explore a network connection between all of the three QS systems in A. hydrophila SSU and their cross talk with c-di-GMP, we overproduced a protein with a GGDEF domain, which increases c-di-GMP levels in bacteria, and studied phenotypes and transcriptional profiling of genes involved in biofilm formation and motility of the wild-type (WT) A. hydrophila and its ?qseB mutant. Over-expression of the GGDEF domain-encoding gene (aha0701h) resulted in a significantly reduced motility of the WT A. hydrophila similar to that of the ?qseB mutant. While enhanced protease production was noted in WT A. hydrophila that had increased c-di-GMP, no enzymatic activity was detected in the ?qseB mutant overexpressing the aha0701h gene. Likewise, denser biofilm formation was noted for WT bacteria when c-di-GMP was overproduced compared to its respective control; however, overproduction of c-di-GMP in the ?qseB mutant led to reduced biofilm formation, a finding similar to that noted for the parental A. hydrophila strain. These effects on bacterial motility and biofilm formation in the ?qseB mutant or the mutant with increased c-di-GMP were correlated with altered levels of fleN and vpsT genes. While we noted transcript levels of qseB and qseC genes to be increased in the ahyRI mutant, down-regulation of the ahyR and ahyI genes was observed in the ?qseB mutant, which correlated with decreased protease activity. Finally, an enhanced virulence of WT A. hydrophila with increased c-di-GMP was noted in a mouse model when compared to findings in the parental strain with vector alone. Overall, we conclude that cross talk between AI-1 and QseBC systems exists in A. hydrophila SSU, and c-di-GMP modulation on QseBC system is dependent on the expression of the AI-1 system.

Dataset Information

A variant quorum sensing system in Aeromonas veronii MTCC 3249.

Publications

A variant quorum sensing system in Aeromonas veronii MTCC 3249.

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