ExsA and LcrF recognize similar consensus binding sites, but differences in their oligomeric state influence interactions with promoter DNA

Jessica M. King, Sara Schesser Bartra, Gregory V Plano, Timothy L. Yahr

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

ExsA activates type III secretion system (T3SS) gene expression in Pseudomonas aeruginosa and is a member of the AraC family of transcriptional regulators. AraC proteins contain two helix-turn-helix (HTH) DNA binding motifs. One helix from each HTH motif inserts into the major groove of the DNA to make base-specific contacts with the promoter region. The amino acids that comprise the HTH motifs of ExsA are nearly identical to those in LcrF/VirF, the activators of T3SS gene expression in the pathogenic yersiniae. In this study, we tested the hypothesis that ExsA/LcrF/VirF recognize a common nucleotide sequence. We report that Yersinia pestis LcrF binds to and activates transcription of ExsA-dependent promoters in P. aeruginosa and that plasmid-expressed ExsA complements a Y. pestis lcrF mutant for T3SS gene expression. Mutations that disrupt the ExsA consensus binding sites in both P. aeruginosa and Y. pestis T3SS promoters prevent activation by ExsA and LcrF. Our combined data demonstrate that ExsA and LcrF recognize a common nucleotide sequence. Nevertheless, the DNA binding properties of ExsA and LcrF are distinct. Whereas two ExsA monomers are sequentially recruited to the promoter region, LcrF binds to promoter DNA as a preformed dimer and has a higher capacity to bend DNA. An LcrF mutant defective for dimerization bound promoter DNA with properties similar to ExsA. Finally, we demonstrate that the activators of T3SS gene expression from Photorhabdus luminescens, Aeromonas hydrophila, and Vibrio parahaemolyticus are also sensitive to mutations that disrupt the ExsA consensus binding site.

Original languageEnglish
Pages (from-to)5639-5650
Number of pages12
JournalJournal of Bacteriology
Volume195
Issue number24
DOIs
StatePublished - Dec 1 2013

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Yersinia pestis
Binding Sites
Helix-Turn-Helix Motifs
DNA
Pseudomonas aeruginosa
Gene Expression
Genetic Promoter Regions
AraC Transcription Factor
Photorhabdus
Vibrio parahaemolyticus
Aeromonas hydrophila
Yersinia
Mutation
Nucleotide Motifs
Dimerization
Plasmids
Amino Acids
Proteins

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology

Cite this

ExsA and LcrF recognize similar consensus binding sites, but differences in their oligomeric state influence interactions with promoter DNA. / King, Jessica M.; Bartra, Sara Schesser; Plano, Gregory V; Yahr, Timothy L.

In: Journal of Bacteriology, Vol. 195, No. 24, 01.12.2013, p. 5639-5650.

Research output: Contribution to journalArticle

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