PMID:24142246

Citation	King, JM, Schesser Bartra, S, Plano, G and Yahr, TL (2013) ExsA and LcrF recognize similar consensus binding sites, but differences in their oligomeric state influence interactions with promoter DNA. J. Bacteriol. 195:5639-50
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.
Links	PubMed PMC3889609 Online version:10.1128/JB.00990-13
Keywords	Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Binding Sites; DNA Mutational Analysis; DNA, Bacterial/metabolism; Gene Expression Regulation, Bacterial; Genetic Complementation Test; Promoter Regions, Genetic; Protein Binding; Protein Multimerization; Pseudomonas aeruginosa/genetics; Recombinant Fusion Proteins/genetics; Recombinant Fusion Proteins/metabolism; Trans-Activators/genetics; Trans-Activators/metabolism; Yersinia pestis/genetics
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
PSEAE:EXSA	involved_in	GO:2000144: positive regulation of DNA-templated transcription, initiation	ECO:0000314: direct assay evidence used in manual assertion		P		Seeded From UniProt	complete
PSEAE:EXSA		GO:2000144: positive regulation of DNA-templated transcription, initiation	ECO:0000314:		P		Figure 8 shows that the binding site is required for transcription activation, but the paper already established activation via IDA in Fig 7	complete CACAO 9763
YERE1:E7BAZ6		GO:2000144: positive regulation of DNA-templated transcription, initiation	ECO:0000314:		P		Figure 1	complete CACAO 9762

References

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