ExsD is a negative regulator of the Pseudomonas aeruginosa type III secretion regulon

Michelle L McCaw; Guinevere L Lykken; Pradeep K Singh; Timothy L Yahr

doi:10.1046/j.1365-2958.2002.03228.x

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ExsD is a negative regulator of the Pseudomonas aeruginosa type III secretion regulon

Journal article

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ExsD is a negative regulator of the Pseudomonas aeruginosa type III secretion regulon

Michelle L McCaw, Guinevere L Lykken, Pradeep K Singh and Timothy L Yahr

Molecular microbiology, Vol.46(4), pp.1123-1133

11/2002

DOI: 10.1046/j.1365-2958.2002.03228.x

PMID: 12421316

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Abstract

Expression of the Pseudomonas aeruginosa type III secretion system is induced by contact with eukaryotic cells, serum or low Ca2+ concentrations. We report that ExsD, a unique protein, is a negative regulator of the type III regulon. Localization studies indicate that ExsD is not secreted by P. aeruginosa. To determine the role of exsD, a non-polar deletion was returned to the chromosome by allelic exchange. The delta exsD mutant is competent for type III secretion and translocation of the ExoU cytotoxin to eukaryotic host cells. To examine the effect of ExsD on transcription, lacZ transcriptional reporter fusions were integrated into the chromosome. Promoters controlling transcription of genes encoding the type III secretory, regulatory and effector proteins demonstrated significant derepression in the delta exsD background. Expression of ExsD from a multicopy plasmid completely repressed transcription of the regulon. Although a mutant in pscC, encoding a structural component of the type III translocase, is repressed for expression of the regulon, a delta exsD, pscC:: omega double mutant is derepressed. Bacterial two-hybrid data indicate that ExsD binds the transcriptional activator of the regulon, ExsA. We conclude that ExsD is a negative regulator and propose that ExsD functions as an ExsA antiactivator to regulate transcription of the regulon.

Calcium - metabolism

Lipoproteins - genetics

Bacterial Proteins - genetics

Repressor Proteins - genetics

Gene Dosage

DNA-Binding Proteins - genetics

Protein Transport

DNA-Binding Proteins - metabolism

Regulon

Pseudomonas aeruginosa - genetics

Pseudomonas aeruginosa - metabolism

Lipoproteins - metabolism

Trans-Activators - genetics

Bacterial Proteins - metabolism

Trans-Activators - metabolism

Transcription, Genetic

Mutation

Gene Expression Regulation, Bacterial

Repressor Proteins - metabolism

Details

Title: Subtitle: ExsD is a negative regulator of the Pseudomonas aeruginosa type III secretion regulon
Creators: Michelle L McCaw - Department of Microbiology, University of Iowa, Iowa City 52242-1101, USA
Guinevere L Lykken
Pradeep K Singh
Timothy L Yahr
Resource Type: Journal article
Publication Details: Molecular microbiology, Vol.46(4), pp.1123-1133
DOI: 10.1046/j.1365-2958.2002.03228.x
PMID: 12421316
NLM abbreviation: Mol Microbiol
ISSN: 0950-382X
eISSN: 1365-2958
Publisher: England
Grant note: R01 AI055042 / NIAID NIH HHS
Language: English
Date published: 11/2002
Academic Unit: Microbiology and Immunology
Record Identifier: 9984001114402771

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