An in vivo inducible gene of Pseudomonas aeruginosa encodes an anti-ExsA to suppress the type III secretion system.
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 (Pseudomonas type III repressor 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.
Department of Molecular Genetics and Microbiology, PO Box 100266, University of Florida, Gainesville, FL 32610, USA.
Un-Hwan
UH
Ha
Jaewha
J
Kim
Hassan
H
Badrane
Jinghua
J
Jia
Henry V
HV
Baker
Donghai
D
Wu
Shouguang
S
Jin
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003300:Copper / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D051379:Mice; D020411:Oligonucleotide Array Sequence Analysis; D011550:Pseudomonas aeruginosa / Q000235:genetics* / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C095092:ExsA protein, bacteria; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D015534:Trans-Activators; D003300:Copper