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 Palacios, S.
Right arrow Articles by Escalante-Semerena, J. C.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Palacios, S.
Right arrow Articles by Escalante-Semerena, J. C.

 Previous Article  |  Next Article 

Journal of Bacteriology, February 2000, p. 905-910, Vol. 182, No. 4
0021-9193/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.

prpR, ntrA, and ihf Functions Are Required for Expression of the prpBCDE Operon, Encoding Enzymes That Catabolize Propionate in Salmonella enterica Serovar Typhimurium LT2

Sergio Palacios and Jorge C. Escalante-Semerena*

Department of Bacteriology, University of Wisconsin---Madison, Madison, Wisconsin

Received 13 September 1999/Accepted 17 November 1999

The genes required for the catabolism of propionate in Salmonella enterica serovar Typhimurium are organized as two transcriptional units (prpR and prpBCDE) that are divergently transcribed from one another. Sequence homology to genes encoding members of the sigma-54 family of transcriptional activators and the identification of a consensus sigma-54 promoter 5' to the prpBCDE operon suggested that PrpR was required to activate expression of this operon. We isolated insertions in prpR and showed that prpR function was needed for growth on propionate as a carbon and energy source. A medium-copy-number plasmid carrying the lacZ gene under the control of the native sigma-54 promoter of prpBCDE was used to study prpBCDE operon expression. Transcription of the lacZ reporter in prpR, ntrA, and ihfB mutants was 85-, 83-, and 15-fold lower than the level of transcription measured in strains carrying the wild-type allele of the gene tested. These data indicated that PrpR, IHF, and transcription sigma factor RpoN were required for the expression of the prpBCDE operon. Further analysis of the involvement of the integration host factor (IHF) protein in the expression of this operon is required due to the well-documented pleiotropic effect the lack of this global regulator has on gene expression. Deletion of the 5' 615-bp portion of the prpR gene resulted in a PrpRc mutant protein that activated prpBCDE transcription regardless of the ability of the strain to synthesize 2-methylcitrate, the putative coactivator of PrpR. These results indicate that the N terminus of PrpR is the coactivator-sensing domain of the protein. When placed under the control of the arabinose-inducible promoter ParaBAD, expression of prpRc allele by arabinose had a strong negative effect on growth of the cell. It is proposed that this deleterious effect of PrpRc may be due to an uncontrolled ATPase activity of PrpR or to cross-activation of genes whose functions negatively affect cell growth under the conditions tested.

* Corresponding author. Mailing address: Department of Bacteriology, University of Wisconsin---Madison, 1550 Linden Dr., Madison, WI 53706-1567. Phone: (608) 262-7379. Fax: (608) 262-9865. E-mail: jcescala{at}facstaff.wisc.edu.

Journal of Bacteriology, February 2000, p. 905-910, Vol. 182, No. 4
0021-9193/00/$04.00+0
Copyright © 2000, 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 © 2000 by the American Society for Microbiology. All rights reserved.