title: Identification of mycobacterial sigma factor binding sites by chromatin immunoprecipitation assays.
abstract: Mycobacterium tuberculosis and Mycobacterium bovis are responsible for infections that cause a substantial amount of death, suffering, and loss around the world. Still, relatively little is known about the mechanisms of gene expression in these bacteria. Here, we used genome-wide location assays to identify direct target genes for mycobacterial sigma factors. Chromatin immunoprecipitation assays were performed with M. bovis BCG for Myc-tagged proteins expressed using an anhydrotetracycline-inducible promoter, and enriched DNA fragments were hybridized to a microarray representing intergenic regions from the M. tuberculosis H37Rv genome. Several putative target genes were validated by quantitative PCR. The corresponding transcriptional start sites were identified for sigma(F), sigma(C), and sigma(K), and consensus promoter sequences are proposed. Our conclusions were supported by the results of in vitro transcription assays. We also examined the role of each holoenzyme in the expression of sigma factor genes. Our results revealed that many sigma factors are expressed from autoregulated promoters.
authors.affiliation: Département de biologie, Université de Sherbrooke, 2500 boulevard de l'Université, Sherbrooke, Québec, Canada J1K 2R1.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Rodrigue
authors.forename: Joëlle
authors.initials: J
authors.lastname: Brodeur
authors.forename: Pierre-Etienne
authors.initials: PE
authors.lastname: Jacques
authors.forename: Alain L
authors.initials: AL
authors.lastname: Gervais
authors.forename: Ryszard
authors.initials: R
authors.lastname: Brzezinski
authors.forename: Luc
authors.initials: L
authors.lastname: Gaudreau
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D047369:Chromatin Immunoprecipitation / Q000379:methods*; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D009163:Mycobacterium bovis / Q000235:genetics*; D009169:Mycobacterium tuberculosis / Q000235:genetics*; D011401:Promoter Regions, Genetic; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; C064971:FliA protein, Bacteria; D012808:Sigma Factor