Abstract

The mechanisms organisms used to adapt to osmotic stress are not understood very extensively. The experiments in this grant proposal are aimed at the elucidation of two aspects of osmotic adaptation in the bacterium Salmonella typhimurium. Two compounds, proline and glycinebetaine, can alleviate the inhibitory effects of osmotic stress in S. typhimurium. These two compounds are taken up by a transport system that is encoded in the proU operon, which is subject to osmotic regulation such that the exposure of the cells to osmotic stress results in a 200-fold induction of its transcription. We shall carry out experiments to elucidate the mechanism of the transcriptional control of the proU operon. The mode of action of proline and glycinebetaine in alleviating osmotic inhibition is not known. We isolated S. typhimurium mutants which are not stimulated by glycinebetaine in media of high osmolarity. We shall carry out a genetic and biochemical analysis of these mutants in order to discover the mechanism whereby glycinebetaine can overcome the inhibitory effects of osmotic stress in the wild type strain. Because there are close similarities in the cellular responses of plants and bacteria to osmotic stress, the insights gained into the osmotic adaptation in bacteria will aid the understanding of this process in plants. Our analysis of the transcriptional control of the proU operon also has potential applications for biotechnology. The promoter of this operon could be fused to desired genes of industrial utility. Over- production of the proteins encoded by these genes could be triggered by the addition of high concentrations of nutrients, which would be required at the same time for the production of large quantities of cells.

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM031944-08
Application #
3280382
Study Section
Microbial Physiology and Genetics Subcommittee 2 (MBC)
Project Start
1983-09-27
Project End
1994-11-30
Budget Start
1991-12-01
Budget End
1992-11-30
Support Year
8
Fiscal Year
1992
Total Cost
Indirect Cost

  Institution

Name
Purdue University
Department
Type
Schools of Arts and Sciences
DUNS #
072051394
City
West Lafayette
State
IN
Country
United States
Zip Code
47907

  Publications

Frymier, J S; Reed, T D; Fletcher, S A et al. (1997) Characterization of transcriptional regulation of the kdp operon of Salmonella typhimurium. J Bacteriol 179:3061-3
Zhang, X; Fletcher, S A; Csonka, L N (1996) Site-directed mutational analysis of the osmotically regulated proU promoter of Salmonella typhimurium. J Bacteriol 178:3377-9
Gutierrez, J A; Csonka, L N (1995) Isolation and characterization of adenylate kinase (adk) mutations in Salmonella typhimurium which block the ability of glycine betaine to function as an osmoprotectant. J Bacteriol 177:390-400
Fletcher, S A; Csonka, L N (1995) Fine-structure deletion analysis of the transcriptional silencer of the proU operon of Salmonella typhimurium. J Bacteriol 177:4508-13
Csonka, L N; Ikeda, T P; Fletcher, S A et al. (1994) The accumulation of glutamate is necessary for optimal growth of Salmonella typhimurium in media of high osmolality but not induction of the proU operon. J Bacteriol 176:6324-33
Overdier, D G; Csonka, L N (1992) A transcriptional silencer downstream of the promoter in the osmotically controlled proU operon of Salmonella typhimurium. Proc Natl Acad Sci U S A 89:3140-4
Csonka, L N; Hanson, A D (1991) Prokaryotic osmoregulation: genetics and physiology. Annu Rev Microbiol 45:569-606
Csonka, L N (1989) Physiological and genetic responses of bacteria to osmotic stress. Microbiol Rev 53:121-47
Overdier, D G; Olson, E R; Erickson, B D et al. (1989) Nucleotide sequence of the transcriptional control region of the osmotically regulated proU operon of Salmonella typhimurium and identification of the 5' endpoint of the proU mRNA. J Bacteriol 171:4694-706
Csonka, L N; Gelvin, S B; Goodner, B W et al. (1988) Nucleotide sequence of a mutation in the proB gene of Escherichia coli that confers proline overproduction and enhanced tolerance to osmotic stress. Gene 64:199-205

Showing the most recent 10 out of 14 publications