JB Try AEM Online
Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
This Article
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 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 Virlogeux, I.
Right arrow Articles by Popoff, M. Y.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Virlogeux, I.
Right arrow Articles by Popoff, M. Y.

J. Bacteriol., 03 1996, 1691-1698, Vol 178, No. 6
Copyright © 1996, American Society for Microbiology

Characterization of the rcsA and rcsB genes from Salmonella typhi: rcsB through tviA is involved in regulation of Vi antigen synthesis

I Virlogeux, H Waxin, C Ecobichon, JO Lee and MY Popoff
Unite des Enterobacteries, Institut Pasteur, Paris, France.

Synthesis of Vi antigen, a capsular polysaccharide expressed by Salmonella typhi, is controlled by the viaA and viaB chromosomal loci. It was previously shown that Vi antigen expression was regulated by a system similar to the rcs regulatory system involved in colanic acid synthesis in Escherichia coli. We have cloned the rcsA, rcsB, and rcsC genes from S. typhi. The predicted amino sequences of the RcsA and RcsB proteins showed a high degree of similarity to their E. coli homologs. The nucleotide sequence of the rcsC gene was partially determined and was shown to be homologous to that of its E. coli counterpart. Complementation experiments indicated that rcsB and rcsC were encompassed within the viaA locus. The RcsA protein was not involved in Vi antigen synthesis. In contrast, the RcsB protein acted as a positive regulator of Vi polysaccharide expression. By mRNA and gene fusion analyses, we studied the role of RcsB and TviA, a via-B-encoded regulatory protein characterized previously, in regulating Vi antigen synthesis. The transcriptional start point of tviA mRNA was not influenced by RcsB or TviA. In the absence of RcsB or TviA protein, transcription of tviA gave rise to only a monocistronic tviA-specific mRNA. The presence of RcsB and TriA not only increased the amount of monocistronic tviA-specific mRNA but also resulted in countranscription of tviA and tviB, which is located immediately downstream of tviA on the viaB locus. In addition, TviA protein did not appear to be subject to degradation by the Lon protease. These results strongly suggest that TviA might act in concert with RcsB at the tviA promoter to activate transcription of the genes involved in Vi polymer synthesis in S. typhi in a Lon-independent manner.


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 © 1996 by the American Society for Microbiology. All rights reserved.