Journal article
ExsA Recruits RNA Polymerase to an Extended −10 Promoter by Contacting Region 4.2 of Sigma-70
Journal of bacteriology, Vol.192(14), pp.3597-3607
07/2010
DOI: 10.1128/JB.00129-10
PMCID: PMC2897327
PMID: 20453093
Abstract
ExsA is a member of the AraC family of transcriptional activators and is required for expression of the
Pseudomonas aeruginosa
type III secretion system (T3SS). ExsA-dependent promoters consist of two binding sites for monomeric ExsA located approximately 50 bp upstream of the transcription start sites. Binding to both sites is required for recruitment of σ
70
-RNA polymerase (RNAP) to the promoter. ExsA-dependent promoters also contain putative −35 hexamers that closely match the σ
70
consensus but are atypically spaced 21 or 22 bp from the −10 hexamer. Because several nucleotides located within the putative −35 region are required for ExsA binding, it is unclear whether the putative −35 region makes an additional contribution to transcription initiation. In the present study we demonstrate that the putative −35 hexamer is dispensable for ExsA-independent transcription from the P
exsC
promoter and that deletion of σ
70
region 4.2, which contacts the −35 hexamer, has no effect on ExsA-independent transcription from P
exsC
. Region 4.2 of σ
70
, however, is required for ExsA-dependent activation of the P
exsC
and P
exsD
promoters. Genetic data suggest that ExsA directly contacts region 4.2 of σ
70
, and several amino acids were found to contribute to the interaction.
In vitro
transcription assays demonstrate that an extended −10 element located in the P
exsC
promoter is important for overall promoter activity. Our collective data suggest a model in which ExsA compensates for the lack of a −35 hexamer by interacting with region 4.2 of σ
70
to recruit RNAP to the promoter.
Details
- Title: Subtitle
- ExsA Recruits RNA Polymerase to an Extended −10 Promoter by Contacting Region 4.2 of Sigma-70
- Creators
- Christopher A Vakulskas - Department of Microbiology, University of Iowa, Iowa City, IowaEvan D Brutinel - Department of Microbiology, University of Iowa, Iowa City, IowaTimothy L Yahr - Department of Microbiology, University of Iowa, Iowa City, Iowa
- Resource Type
- Journal article
- Publication Details
- Journal of bacteriology, Vol.192(14), pp.3597-3607
- DOI
- 10.1128/JB.00129-10
- PMID
- 20453093
- PMCID
- PMC2897327
- NLM abbreviation
- J Bacteriol
- ISSN
- 0021-9193
- eISSN
- 1098-5530
- Publisher
- American Society for Microbiology (ASM)
- Language
- English
- Date published
- 07/2010
- Academic Unit
- Microbiology and Immunology
- Record Identifier
- 9984001209602771
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