title: Yeast Rrn7 and human TAF1B are TFIIB-related RNA polymerase I general transcription factors.
abstract: Eukaryotic and archaeal multisubunit RNA polymerases (Pols) are structurally related and require several similar components for transcription initiation. However, none of the Pol I factors were known to share homology with transcription factor IIB (TFIIB) or TFIIB-related proteins, key factors in the initiation mechanisms of the other Pols. Here we show that Rrn7, a subunit of the yeast Pol I core factor, and its human ortholog TAF1B are TFIIB-like factors. Although distantly related, Rrn7 shares many activities associated with TFIIB-like factors. Domain swaps between TFIIB-related factors show that Rrn7 is most closely related to the Pol III general factor Brf1. Our results point to the conservation of initiation mechanisms among multisubunit Pols and reveal a key function of yeast core factor/human SL1 in Pol I transcription.
authors.affiliation: Fred Hutchinson Cancer Research Center, Division of Basic Sciences, 1100 Fairview Avenue N, Post Office Box 19024, Mailstop A1-162, Seattle, WA 98109, USA.
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Knutson
authors.forename: Steven
authors.initials: S
authors.lastname: Hahn
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D006801:Humans; D008969:Molecular Sequence Data; D035463:Pol1 Transcription Initiation Complex Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017510:Protein Folding; D054730:Protein Interaction Domains and Motifs; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012318:RNA Polymerase I / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D035181:TATA-Box Binding Protein / Q000378:metabolism; D035581:Transcription Factor TFIIB / Q000737:chemistry / Q000378:metabolism; D035361:Transcription Factor TFIIIB / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: C090956:BRF1 protein, S cerevisiae; D035463:Pol1 Transcription Initiation Complex Proteins; C090315:RRN7 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C091129:TAF1B protein, human; D035181:TATA-Box Binding Protein; D035581:Transcription Factor TFIIB; D035361:Transcription Factor TFIIIB; D012318:RNA Polymerase I