title: The interface of sigma with core RNA polymerase is extensive, conserved, and functionally specialized.
abstract: The sigma subunit of eubacterial RNA polymerase is required throughout initiation, but how it communicates with core polymerase (alpha(2)betabeta') is poorly understood. The present work addresses the location and function of the interface of sigma with core. Our studies suggest that this interface is extensive as mutations in six conserved regions of sigma(70) hinder the ability of sigma to bind core. Direct binding of one of these regions to core can be demonstrated using a peptide-based approach. The same regions, and even equivalent residues, in sigma(32) and sigma(70) alter core interaction, suggesting that sigma(70) family members use homologous residues, at least in part, to interact with core. Finally, the regions of sigma that we identify perform specialized functions, suggesting that different portions of the interface perform discrete roles during transcription initiation.
authors.affiliation: University of California, San Francisco, San Francisco, California 94143, USA.
authors.forename: M M
authors.initials: MM
authors.lastname: Sharp
authors.forename: C L
authors.initials: CL
authors.lastname: Chan
authors.forename: C Z
authors.initials: CZ
authors.lastname: Lu
authors.forename: M T
authors.initials: MT
authors.lastname: Marr
authors.forename: S
authors.initials: S
authors.lastname: Nechaev
authors.forename: E W
authors.initials: EW
authors.lastname: Merritt
authors.forename: K
authors.initials: K
authors.lastname: Severinov
authors.forename: J W
authors.initials: JW
authors.lastname: Roberts
authors.forename: C A
authors.initials: CA
authors.lastname: Gross
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D011487:Protein Conformation; D012318:RNA Polymerase I / Q000737:chemistry* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D012808:Sigma Factor / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D006360:Heat-Shock Proteins; D011993:Recombinant Fusion Proteins; D012808:Sigma Factor; D014157:Transcription Factors; C069774:heat-shock sigma factor 32; C081775:RNA polymerase sigma 70; D012321:DNA-Directed RNA Polymerases; D012318:RNA Polymerase I