Rajkumari, K. ; Ishihama, A. ; Gowrishankar, J. (1997) Evidence for transcription attenuation rendering cryptic a sigmaS- dependent promoter of the osmotically regulated proU operon of Salmonella typhimurium Journal of Bacteriology, 179 (22). pp. 7169-7173. ISSN 0021-9193
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Official URL: http://jb.asm.org/cgi/content/abstract/179/22/7169
Abstract
The osmotically regulated proU locus in Escherichia coli has two promoters, P1 and P2, that are recognized, respectively, by the σ S- and σ 70-bearing RNA polymerase holoenzymes. However, the equivalent of the P1 promoter does not appear to exist in Salmonella typhimurium. We demonstrate in this study that wild-type S. typhimurium has a cryptic P1 promoter that is recognized by σ S RNA polymerase in vitro and that a 22-bp deletion from +63 to +84 (relative to the start site of transcription) confers σ S-dependent in vivo expression of a reporter gene fusion to P1. Primer extension analysis of RNA isolated from cells carrying the wild-type and mutant S. typhimurium proU constructs indicated that a primer which hybridizes proximal to +60 is able to detect P1-initiated transcripts from both constructs but a primer which hybridizes distal to +85 is able to do so only from the latter. Our results suggest that the σ S-controlled proU P1 promoter in S. typhimurium may be rendered cryptic because of factor-dependent transcription attenuation within a short distance downstream of the promoter start site.
Item Type: | Article |
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Source: | Copyright of this article belongs to American Society for Microbiology. |
ID Code: | 16943 |
Deposited On: | 16 Nov 2010 13:16 |
Last Modified: | 17 May 2016 01:39 |
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