The bacterium Escherichia coli can survive in a wide variety of environments due to its ability to rapidly adapt to changing conditions via a repertoire of stress responses. One type of stress is an increase in the osmotic strength of the growth medium; the ability to adapt is relevant to the bacterium's survival in the human bladder and colon, sewage systems, and seawater. Adaptive alterations in cellular metabolism and structure are mediated by the products of certain osmotically responsive genes. Our primary goal is to understand the molecular mechanisms governing osmotically dependent gene expression. An excellent experimental model is proU, a locus which encodes a transport system for the ubiquitous osmoprotectant glycine betaine. proU is induced strongly and rapidly in response to the changes in intracellular ion composition that accompany osmotic stress. Transcription activation in vitro requires only the DNA template, RNA polymerase and potassium glutamate. Genetic manipulation of both the promoter and RNA polymerase and biochemical dissection of events effected by potassium glutamate will provide the molecular details of this unique type of transcriptional control. The analysis will be extended to other genes responding to osmotic signals to determine whether there is a common regulatory mechanism. osmb, which encodes a structural lipoprotein, is representative of a class of genes that are induced by two signals, growth in hyperosmotic media and stationary phase. In vitro gene expression will determine the signal transduction mechanism for each of these stimuli and, along with genetic approaches, identify necessary trans-acting regulatory factors.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
2R01GM033778-07
Application #
3283765
Study Section
Microbial Physiology and Genetics Subcommittee 2 (MBC)
Project Start
1984-12-01
Project End
1994-07-31
Budget Start
1991-08-01
Budget End
1992-07-31
Support Year
7
Fiscal Year
1991
Total Cost
Indirect Cost
Name
University of California Davis
Department
Type
Schools of Earth Sciences/Natur
DUNS #
094878337
City
Davis
State
CA
Country
United States
Zip Code
95618
Wise, A; Brems, R; Ramakrishnan, V et al. (1996) Sequences in the -35 region of Escherichia coli rpoS-dependent genes promote transcription by E sigma S. J Bacteriol 178:2785-93
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
Meyer, S E; Granett, S; Jung, J U et al. (1990) Osmotic regulation of PhoE porin synthesis in Escherichia coli. J Bacteriol 172:5501-2
Jung, J U; Gutierrez, C; Villarejo, M R (1989) Sequence of an osmotically inducible lipoprotein gene. J Bacteriol 171:511-20
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

Showing the most recent 10 out of 11 publications