The two-component QseBC signalling system regulates in vitro and in vivo virulence of Aeromonas hydrophila

Bijay K. Khajanchi, Elena V. Kozlova, Jian Sha, Vsevolod Popov, Ashok Chopra

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Abstract

We recently demonstrated that the N-acyl-homoserine lactone [autoinducer (AI)-1] and LuxS (AI-2)-based quorum-sensing (QS) systems exerted positive and negative regulation, respectively, on the virulence of a diarrhoeal isolate SSU of Aeromonas hydrophila. However, the role of a newly identified, two-component-based QseBC QS system in the regulation of bacterial virulence in general is not well understood, with only a limited number of studies showing its function in bacterial pathogenesis. In this report, we identified and characterized the QseBC QS system in A. hydrophila SSU and found that, as was the case with enterohaemorrhagic Escherichia coli, the open reading frames for the qseB (the response regulator) and qseC (the sensor histidine kinase) genes overlapped by 4 bp at the ATGA motif. Our data provide evidence that deletion of the qseB gene from A. hydrophila resulted in attenuation of bacterial virulence in a septicaemic mouse model of infection and diminished swimming and swarming motility, and the mutant bacteria formed denser biofilms compared with those from the parental strain of A. hydrophila. The decrease in the virulence of the A. hydrophila ΔqseB mutant correlated with reduced production of protease and the cytotoxic enterotoxin, which has associated haemolytic activity. The swimming and swarming motility, haemolytic activity, protease production and biofilm formation were restored in the qseBC-complemented strain to a level similar to that of the wild-type A. hydrophila SSU. Our study is the first, to our knowledge, to report a functional QseBC QS system in A. hydrophila which may be linked to AI-1 and AI-2 QS systems in modulating bacterial virulence, possibly through the cyclic diguanosine monophosphate.

Original languageEnglish (US)
Pages (from-to)259-271
Number of pages13
JournalMicrobiology
Volume158
Issue number1
DOIs
StatePublished - Jan 2012

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Aeromonas hydrophila
Quorum Sensing
Virulence
Biofilms
Peptide Hydrolases
Acyl-Butyrolactones
Enterohemorrhagic Escherichia coli
Enterotoxins
Gene Deletion
In Vitro Techniques
Open Reading Frames
Bacteria
Infection

ASJC Scopus subject areas

  • Microbiology

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The two-component QseBC signalling system regulates in vitro and in vivo virulence of Aeromonas hydrophila. / Khajanchi, Bijay K.; Kozlova, Elena V.; Sha, Jian; Popov, Vsevolod; Chopra, Ashok.

In: Microbiology, Vol. 158, No. 1, 01.2012, p. 259-271.

Research output: Contribution to journalArticle

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