The research proposed in this application is designed to unravel the complex pleiotropic molecular response to Salmonella typhimurium to physiologic stress. Techniques which simplify the construction of gene fusions will be used to place the gene responsible for B-galactosidase, lacZ, under the control of promoters which regulate the response of starvation-inducible or starvation repressible genetic loci. Each fusion will be examined for responses to nicotinate, phosphate, amino acid, thiamine, sulfur and carbon limitations. Preference will be given to those fusions which respond to several different conditions. Starvation regulated stimulons revealed through these studies will be examined in terms of induction kinetics, the effect of various loci known to control different regulons (recA, relA, cya) and genetic map position. Through two dimensional gel electrophoretic techniques the gene product for each starvation-regulated locus will be identified. In addition, two dimensional thin-layer chromotography will be used in conjunction with 32P-labeling techniques to identify potential cellular alarmones which may be involved in the regulation of these regulons. The effort outline may be viewed as an early step toward developing a unified theory of the genetic and physiologic response toward environmental stress.
