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An in vivo inducible gene of Pseudomonas aeruginosa encodes an anti‐ExsA to suppress the type III secretion system
Author(s) -
Ha UnHwan,
Kim Jaewha,
Badrane Hassan,
Jia Jinghua,
Baker Henry V.,
Wu Donghai,
Jin Shouguang
Publication year - 2004
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2004.04282.x
Subject(s) - biology , repressor , pseudomonas aeruginosa , secretion , type three secretion system , gene , open reading frame , regulation of gene expression , activator (genetics) , microbiology and biotechnology , gene expression , genetics , bacteria , mutant , biochemistry , peptide sequence
Summary We have previously reported on the isolation of in vivo inducible genes of Pseudomonas aeruginosa using IVET system. One of such genes isolated from burn mouse infection model encodes a short open reading frame with unknown function. In this study, we demonstrate that this gene product specifically suppresses the expression of type III secretion genes in P. aeruginosa , thus named PtrA ( P seudomonas t ype III r epressor A ). A direct interaction between the PtrA and type III transcriptional activator ExsA was demonstrated, suggesting that its repressor function is probably realized through inhibition of the ExsA protein function. Indeed, an elevated expression of the exsA compensates the repressor effect of the PtrA. Interestingly, expression of the ptrA is highly and specifically induced by copper cation. A copper‐ responsive two‐component regulatory system, copR‐copS , has also been identified and shown to be essential for the copper resistance in P. aeruginosa as well as the activation of ptrA in response to the copper signal. Elevated expression of the ptrA during the infection of mouse burn wound suggests that P. aeruginosa has evolved tight regulatory systems to shut down energy‐expensive type III secretion apparatus in response to specific environmental signals, such as copper stress.