Affiliation:
1. School of Pharmaceutical Sciences
2. Institute of Infections and Immunity, University Park, University of Nottingham, Nottingham NG7 2RD, United Kingdom
3. Laboratoire d’Ingénierie des Systèmes Moléculaires, Centre National de la Recherche Scientifique, 13402 Marseille Cedex 20, France
Abstract
ABSTRACT
Pseudomonas aeruginosa
regulates the production of many exoproteins and secondary metabolites via a hierarchical quorum-sensing cascade through LasR and RhlR and their cognate signal molecules
N-
(3-oxododecanoyl)-
l
-homoserine lactone (3O-C12-HSL) and
N-
(butanoyl)-
l
-homoserine lactone (C4-HSL). In this study, we found that transcription of the quorum sensing-regulated genes
lecA
(coding for PA-IL lectin),
lasB
(coding for elastase), and
rpoS
appeared to be growth phase dependent and their expression could not be advanced to the logarithmic phase in cells growing in batch culture by the addition of exogenous C4-HSL and 3O-C12-HSL. To identify novel regulators responsible for this growth phase dependency, a
P. aeruginosa lecA
::
lux
reporter strain was subjected to random transposon mutagenesis. A number of mutants affected in
lecA
expression were found that exhibited altered production of multiple quorum sensing-dependent phenotypes. While some mutations were mapped to new loci such as
clpA
and
mvaT
and a putative efflux system, a number of mutations were also mapped to known regulators such as
lasR
,
rhlR
, and
rpoS.
MvaT was identified as a novel global regulator of virulence gene expression, as a mutation in
mvaT
resulted in enhanced
lecA
expression and pyocyanin production. This mutant also showed altered swarming ability and production of the LasB and LasA proteases, 3O-C12-HSL, and C4-HSL. Furthermore, addition of exogenous 3O-C12-HSL and C4-HSL to the
mvaT
mutant significantly advanced
lecA
expression, suggesting that MvaT is involved in the growth phase-dependent regulation of the
lecA
gene.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
211 articles.
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