title: Further characterization of functional domains of PerA, role of amino and carboxy terminal domains in DNA binding.
abstract: PerA is a key regulator of virulence genes in enteropathogenic E. coli. PerA is a member of the AraC/XylS family of transcriptional regulators that directly regulates the expression of the bfp and per operons in response to different environmental cues. Here, we characterized mutants in both the amino (NTD) and carboxy (CTD) terminal domains of PerA that affect its ability to activate the expression of the bfp and per promoters. Mutants at residues predicted to be important for DNA binding within the CTD had a significant defect in their ability to bind to the regulatory regions of the bfp and per operons and, consequently, in transcriptional activation. Notably, mutants in specific NTD residues were also impaired to bind to DNA suggesting that this domain is involved in structuring the protein for correct DNA recognition. Mutations in residues E116 and D168, located in the vicinity of the putative linker region, significantly affected the activation of the perA promoter, without affecting PerA binding to the per or bfp regulatory sequences. Overall these results provide additional evidence of the importance of the N-terminal domain in PerA activity and suggest that the activation of these promoters involves differential interactions with the transcriptional machinery. This study further contributes to the characterization of the functional domains of PerA by identifying critical residues involved in DNA binding, differential promoter activation and, potentially, in the possible response to environmental cues.
authors: Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México. ibarraj@usf.edu
authors: J Antonio
authors: JA
authors: Ibarra
authors: Claudia M
authors: CM
authors: García-Zacarias
authors: Cristina
authors: C
authors: Lara-Ochoa
authors: Alejandro
authors: A
authors: Carabarin-Lima
authors: J Sergio
authors: JS
authors: Tecpanecatl-Xihuitl
authors: Ernesto
authors: E
authors: Perez-Rueda
authors: Ygnacio
authors: Y
authors: Martínez-Laguna
authors: José L
authors: JL
authors: Puente
mesh_terms: D005260:Female; D006801:Humans; D008297:Male; D009038:Motion; D012737:Sex Factors; D014796:Visual Perception