OmpR regulates the stationary-phase acid tolerance response of Salmonella enterica serovar typhimurium.
Tolerance to acidic environments is an important property of free-living and pathogenic enteric bacteria. Salmonella enterica serovar Typhimurium possesses two general forms of inducible acid tolerance. One is evident in exponentially growing cells exposed to a sudden acid shock. The other is induced when stationary-phase cells are subjected to a similar shock. These log-phase and stationary-phase acid tolerance responses (ATRs) are distinct in that genes identified as participating in log-phase ATR have little to no effect on the stationary-phase ATR (I. S. Lee, J. L. Slouczewski, and J. W. Foster, J. Bacteriol. 176:1422-1426, 1994). An insertion mutagenesis strategy designed to reveal genes associated with acid-inducible stationary-phase acid tolerance (stationary-phase ATR) yielded two insertions in the response regulator gene ompR. The ompR mutants were defective in stationary-phase ATR but not log-phase ATR. EnvZ, the known cognate sensor kinase, and the porin genes known to be controlled by OmpR, ompC and ompF, were not required for stationary-phase ATR. However, the alternate phosphodonor acetyl phosphate appears to play a crucial role in OmpR-mediated stationary-phase ATR and in the OmpR-dependent acid induction of ompC. This conclusion was based on finding that a mutant form of OmpR, which is active even though it cannot be phosphorylated, was able to suppress the acid-sensitive phenotype of an ack pta mutant lacking acetyl phosphate. The data also revealed that acid shock increases the level of ompR message and protein in stationary-phase cells. Thus, it appears that acid shock induces the production of OmpR, which in its phosphorylated state can trigger expression of genes needed for acid-induced stationary-phase acid tolerance.
Bang
I S
IS
Graduate School of Biotechnology, Korea University, Seoul 136701, Korea.
Kim
B H
BH
Foster
J W
JW
Park
Y K
YK
D000143:Acids / Q000494:pharmacology*; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins; D004352:Drug Resistance, Microbial / Q000235:genetics; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D006863:Hydrogen-Ion Concentration; D009097:Multienzyme Complexes; D010755:Organophosphates / Q000378:metabolism; D010766:Phosphorylation; D018272:Porins / Q000096:biosynthesis; D012486:Salmonella typhimurium / Q000187:drug effects / Q000235:genetics* / Q000276:immunology; D012703:Serotyping; D015534:Trans-Activators / Q000378:metabolism*
D000143:Acids; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D009097:Multienzyme Complexes; C113724:OmpC protein; D010755:Organophosphates; D018272:Porins; D015534:Trans-Activators; C112177:osmolarity response regulator proteins; C011632:acetyl phosphate; C057843:envZ protein, E coli