The distal ExsA-binding site in Pseudomonas aeruginosa type III secretion system promoters is the primary determinant for promoter-specific properties

Evan D Brutinel; Jessica M King; Anne E Marsden; Timothy L Yahr

doi:10.1128/JB.00106-12

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The distal ExsA-binding site in Pseudomonas aeruginosa type III secretion system promoters is the primary determinant for promoter-specific properties

Journal article

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The distal ExsA-binding site in Pseudomonas aeruginosa type III secretion system promoters is the primary determinant for promoter-specific properties

Evan D Brutinel, Jessica M King, Anne E Marsden and Timothy L Yahr

Journal of bacteriology, Vol.194(10), pp.2564-2572

05/2012

DOI: 10.1128/JB.00106-12

PMCID: PMC3347217

PMID: 22408165

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Abstract

Transcription of the Pseudomonas aeruginosa type III secretion system is controlled by ExsA, a member of the AraC/XylS family of regulators. Each ExsA-dependent promoter contains two adjacent binding sites for monomeric ExsA. The promoter-proximal site (binding site 1) consists of highly conserved GnC and TGnnA sequences that are individually recognized by the two helix-turn-helix (HTH) DNA-binding motifs of an ExsA monomer. While the GnC and TGnnA sequences are important for binding to site 1, the promoter-distal binding sites (site 2) lack obvious similarity among themselves or with binding site 1. In the present study, we demonstrate that site 2 in the P(exsC) promoter region contains a GnC sequence that is functionally equivalent to the GnC in site 1 and recognized by the first HTH motif of an ExsA monomer. Likewise, the second HTH interacts with an adenine residue in binding site 2. Although several candidate GnC sequences are also present in site 2 of the P(exsD), P(exoT), and P(pcrG) promoters, the GnC sequences were not required for ExsA-dependent transcription or ExsA binding. A comparison of hybrid promoters composed of binding site 2 from one promoter fused to binding site 1 derived from another promoter indicates that ExsA-binding affinity, promoter strength, and the degree of promoter bending are properties that are largely determined by binding site 2. Based on these data, we propose that the manner in which ExsA interacts with binding site 2 at the P(exsC) promoter is distinct from the interactions occurring at other promoters.

Mutagenesis

Mutation

Bacterial Proteins - genetics

Promoter Regions, Genetic - genetics

Recombinant Fusion Proteins - metabolism

Gene Expression Regulation, Bacterial - physiology

DNA, Bacterial

Pseudomonas aeruginosa - genetics

Pseudomonas aeruginosa - metabolism

Base Sequence

Trans-Activators - genetics

Protein Binding

Recombinant Fusion Proteins - genetics

Bacterial Proteins - metabolism

Trans-Activators - metabolism

Binding Sites

Details

Title: Subtitle: The distal ExsA-binding site in Pseudomonas aeruginosa type III secretion system promoters is the primary determinant for promoter-specific properties
Creators: Evan D Brutinel - Department of Microbiology, University of Iowa, Iowa City, Iowa, USA
Jessica M King
Anne E Marsden
Timothy L Yahr
Resource Type: Journal article
Publication Details: Journal of bacteriology, Vol.194(10), pp.2564-2572
Publisher: United States
DOI: 10.1128/JB.00106-12
PMID: 22408165
PMCID: PMC3347217
ISSN: 0021-9193
eISSN: 1098-5530
Grant note: R01-AI055042 / NIAID NIH HHS R01 AI055042 / NIAID NIH HHS
Language: English
Date published: 05/2012
Academic Unit: Microbiology and Immunology
Record Identifier: 9984001129902771

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