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The focus of this project is to: (a) further characterize two such SSR loci, stiA and stiC; and (b) identify additional SSR loci.
One of the most common and persistent environmental stresses encountered by bacteria is starvation for an essential nutrient, such as carbon. The ability to respond to and survive these environmental challenges has a profound effect on bacterial persistence in nature and some animal hosts. Salmonella typhimurium, as well other bacteria, has evolved global response mechanisms, the starvation-stress response or SSR, that not only protect it from the effects of starvation but also provides cross-resistance to other environmental stresses (e.g., thermal, oxidative, or osmotic challenge). Several carbon-starvation-inducible genes have been identified whose products are essential for the survival of S. typhimurium during long-term carbon-starvation and to varying degrees for resistance to other environmental stresses. The focus of this project is to: (a) further characterize two such SSR loci, stiA and stiC; and (b) identify additional SSR loci. To address these goals: (1) the stiA locus will be PCR amplified, cloned,and DNA sequenced. The regulation, expression and function of the gene(s) of the operon that are essential for starvation- and stress-resistance mechanisms will be characterized; (2) the regulation of the stiC gene and an additional hypothetical SSR gene (pbpG) will be analyzed independently and as part of a potential operon; and (3) new potential SSR genes will be identified and characterized. The completion of this project will be critical to the understanding of the basic physiology of the starved/stressed bacterial cell (the "natural" state in which bacteria are found) and the characterization of the starvation-stress response of not only Salmonella but also other bacteria.