JB
Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Cunning, C.
Right arrow Articles by Elliott, T.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Cunning, C.
Right arrow Articles by Elliott, T.

Journal of Bacteriology, August 1999, p. 4853-4862, Vol. 181, No. 16
0021-9193/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.

RpoS Synthesis Is Growth Rate Regulated in Salmonella typhimurium, but Its Turnover Is Not Dependent on Acetyl Phosphate Synthesis or PTS Function

Christofer Cunning and Thomas Elliott*

Department of Microbiology and Immunology, West Virginia University Health Sciences Center, Morgantown, West Virginia 26506

Received 13 April 1999/Accepted 15 June 1999

The RpoS sigma factor of enteric bacteria is either required for or augments the expression of a number of genes that are induced during nutrient limitation, growth into stationary phase, or in response to stresses, including high osmolarity. RpoS is regulated at multiple levels, including posttranscriptional control of its synthesis, protein turnover, and mechanisms that affect its activity directly. Here, the control of RpoS stability was investigated in Salmonella typhimurium by the isolation of a number of mutants specifically defective in RpoS turnover. These included 20 mutants defective in mviA, the ortholog of Escherichia coli rssB/sprE, and 13 mutants defective in either clpP or clpX which encode the protease active on RpoS. An hns mutant was also defective in RpoS turnover, thus confirming that S. typhimurium and E. coli have identical genetic requirements for this process. Some current models predict the existence of a kinase to phosphorylate the response regulator MviA, but no mutants affecting a kinase were recovered. An mviA mutant carrying the D58N substitution altering the predicted phosphorylation site is substantially defective, suggesting that phosphorylation of MviA on D58 is important for its function. No evidence was obtained to support models in which acetyl phosphate or the PTS system contributes to MviA phosphorylation. However, we did find a significant (fivefold) elevation of RpoS during exponential growth on acetate as the carbon and energy source. This behavior is due to growth rate-dependent regulation which increases RpoS synthesis at slower growth rates. Growth rate regulation operates at the level of RpoS synthesis and is mainly posttranscriptional but, surprisingly, is independent of hfq function.

* Corresponding author. Mailing address: Department of Microbiology and Immunology, P.O. Box 9177, WVU Health Sciences Center, Morgantown, WV 26506-9177. Phone: (304) 293-2676. Fax: (304) 293-7823. E-mail: telliott{at}wvu.edu.

Journal of Bacteriology, August 1999, p. 4853-4862, Vol. 181, No. 16
0021-9193/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.


This article has been cited by other articles:



Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
Appl. Environ. Microbiol. Infect. Immun. Eukaryot. Cell
Mol. Cell. Biol. J. Virol. Microbiol. Mol. Biol. Rev.
ALL ASM JOURNALS

Copyright © 1999 by the American Society for Microbiology. All rights reserved.