title: The SKHR motif is required for biological function of the VirR response regulator from Clostridium perfringens.
abstract: The response regulator VirR and its cognate sensor histidine kinase, VirS, are responsible for toxin gene regulation in the human pathogen Clostridium perfringens. The C-terminal domain of VirR (VirRc) contains the functional FxRxHrS motif, which is involved in DNA binding and is conserved in many regulatory proteins. VirRc was cloned, purified, and shown by in vivo and in vitro studies to comprise an independent DNA binding domain. Random and site-directed mutagenesis was used to identify further amino acids that were required for the functional integrity of the protein. Random mutagenesis identified a unique residue, Met-172, that was required for biological function. Site-directed mutagenesis of the SKHR motif (amino acids 216 to 219) revealed that these residues were also required for biological activity. Analysis of the mutated proteins indicated that they were unable to bind to the DNA target with the same efficiency as the wild-type protein.
authors.affiliation: Bacterial Pathogenesis Research Group, Department of Microbiology, Monash University, Victoria 3800, Australia.
authors.forename: Sheena
authors.initials: S
authors.lastname: McGowan
authors.forename: Jennifer R
authors.initials: JR
authors.lastname: O'Connor
authors.forename: Jackie K
authors.initials: JK
authors.lastname: Cheung
authors.forename: Julian I
authors.initials: JI
authors.lastname: Rood
mesh_terms: D020816:Amino Acid Motifs; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D003016:Clostridium perfringens / Q000235:genetics* / Q000378:metabolism; D004269:DNA, Bacterial / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D016296:Mutagenesis; D016297:Mutagenesis, Site-Directed; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D014157:Transcription Factors; C068267:mry protein, Streptococcus pyogenes