title: Roadblock repression of transcription by Bacillus subtilis CodY.
abstract: CodY is a global transcriptional regulator that is known to control, directly or indirectly, expression of more than 100 genes and operons in Bacillus subtilis. Using a combination of mutational analysis and DNase I footprinting experiments, we identified two high-affinity CodY-binding sites that contribute to repression of the ybgE gene and appear to act independently. One of these sites, located 80 bp downstream of the transcription start site, accounted for the bulk of ybgE repression. Using in vitro transcription experiments, we demonstrated that in the presence of CodY, a shorter-than-expected ybgE transcript that terminates at the downstream CodY-binding site was synthesized. Thus, CodY binding to the downstream site represses transcription by a roadblock mechanism. Similar premature termination of transcription was observed for bcaP and yufN, two other CodY-regulated genes with binding sites downstream of the promoter. In accord with the roadblock mechanism, CodY-mediated repression at downstream sites was partly relieved if the transcription-repair coupling factor Mfd was inactivated.
authors.affiliation: Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA. Boris.Belitsky@tufts.edu
authors.forename: Boris R
authors.initials: BR
authors.lastname: Belitsky
authors.forename: Abraham L
authors.initials: AL
authors.lastname: Sonenshein
mesh_terms: D001412:Bacillus subtilis / Q000502:physiology*; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D001665:Binding Sites; D018983:DNA Footprinting; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D012097:Repressor Proteins / Q000235:genetics*; D024363:Transcription Initiation Site; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D012097:Repressor Proteins