Osmotic stress from saline environments is experienced by a wide range of organisms in nature. For example, bacteria expelled into the ocean in sewage and higher plants coping with drying fields must dramatically increase their intracellular osmotic pressure to maintain cellular turgor pressure. Similar osmotic pressure gradients are created in the kidneys of higher animals. There is increasing evidence that these diverse organisms use analogous strategies to cope with the stress. The goal of this research program is to contribute to understanding the molecular mechanisms of adaptation to environmental stress by elucidating the mechanism of osmoregulation; the altered pattern of gene expression brought about by a change in environmental osmotic strength. Escherichia coli's growth and survival in saline environments is greatly enhanced by """"""""osmoprotectants""""""""; small organic molecules that can be accumulated to high internal concentrations without disturbing cellular metabolism. A transport system for the ubiquitous osmoprotectant, glycine betaine, is encoded by the proU operon. This project will analyze the mechanism of induction of the genes encoding the transport system by elevated osmolarity. The role of the osmotically inducible osmB and osmD genes in the adaptative response will be determined by identifying their protein products and functions. A genetic search for regulatory loci will be carried out. The possibility of coordinate regulation of osmotically inducible genes, and common regulatory signals will be examined. The chemical nature of the osmoregulatory signal will be explored in permeabilized cells, in vitro coupled transcription/translation and reconstituted transcription. The technical emphasis is on biochemical analysis of components of the osmotic response, with genetic manipulations aiding and supporting this effort.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM033778-05
Application #
3283769
Study Section
Microbial Physiology and Genetics Subcommittee 2 (MBC)
Project Start
1984-12-01
Project End
1991-07-31
Budget Start
1989-08-01
Budget End
1990-07-31
Support Year
5
Fiscal Year
1989
Total Cost
Indirect Cost
Name
University of California Davis
Department
Type
Earth Sciences/Resources
DUNS #
094878337
City
Davis
State
CA
Country
United States
Zip Code
95618
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Ramirez, R M; Villarejo, M (1991) Osmotic signal transduction to proU is independent of DNA supercoiling in Escherichia coli. J Bacteriol 173:879-85
Prince, W S; Villarejo, M R (1990) Osmotic control of proU transcription is mediated through direct action of potassium glutamate on the transcription complex. J Biol Chem 265:17673-9
Jung, J U; Gutierrez, C; Martin, F et al. (1990) Transcription of osmB, a gene encoding an Escherichia coli lipoprotein, is regulated by dual signals. Osmotic stress and stationary phase. J Biol Chem 265:10574-81
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Ramirez, R M; Prince, W S; Bremer, E et al. (1989) In vitro reconstitution of osmoregulated expression of proU of Escherichia coli. Proc Natl Acad Sci U S A 86:1153-7
Barron, A; Jung, J U; Villarejo, M (1987) Purification and characterization of a glycine betaine binding protein from Escherichia coli. J Biol Chem 262:11841-6
Case, C C; Bukau, B; Granett, S et al. (1986) Contrasting mechanisms of envZ control of mal and pho regulon genes in Escherichia coli. J Bacteriol 166:706-12
Barron, A; May, G; Bremer, E et al. (1986) Regulation of envelope protein composition during adaptation to osmotic stress in Escherichia coli. J Bacteriol 167:433-8

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