Open Accessσ s-Dependent carbon-starvation induction of pbpG (PBP 7) is required for the starvation-stress response in Salmonella enterica serovar Typhimurium
Author(s) -
William J. Kenyon,
LaShae Nicholson,
Bronislava Řežuchová,
Dagmar Homerová,
Francisco Garcı́a-del Portillo,
B. Brett Finlay,
Mark J. Pallen,
Ján Kormanec,
Michael P. Spector
Publication year - 2007
Publication title -
microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.019
H-Index - 179
eISSN - 1465-2080
pISSN - 1350-0872
DOI - 10.1099/mic.0.2007/005199-0
Subject(s) - starvation , salmonella enterica , microbiology and biotechnology , serotype , salmonella , fight or flight response , enterobacteriaceae , bacteria , biology , chemistry , escherichia coli , biochemistry , gene , genetics , endocrinology
Carbon-energy source starvation is a commonly encountered stress that can influence the epidemiology and virulence of Salmonella enterica serovars. Salmonella responds to C-starvation by eliciting the starvation-stress response (SSR), which allows for long-term C-starvation survival and cross-resistance to other stresses. The stiC locus was identified as a C-starvation-inducible, sigma(S)-dependent locus required for a maximal SSR. We report here that the stiC locus is an operon composed of the yohC (putative transport protein) and pbpG (penicillin-binding protein-7/8) genes. yohC pbpG transcription is initiated from a sigma(S)-dependent C-starvation-inducible promoter upstream of yohC. Another (sigma(S)-independent) promoter, upstream of pbpG, drives lower constitutive pbpG transcription, primarily during exponential phase. C-starvation-inducible pbpG expression was required for development of the SSR in 5 h, but not 24 h, C-starved cells; yohC was dispensable for the SSR. Furthermore, the yohC pbpG operon is induced within MDCK epithelial cells, but was not essential for oral virulence in BALB/c mice. Thus, PBP 7 is required for physiological changes, occurring within the first few hours of C-starvation, essential for the development of the SSR. Lack of PBP 7, however, can be compensated for by further physiological changes developed in 24 h C-starved cells. This supports the dynamic overlapping and distinct nature of resistance pathways within the Salmonella SSR.