title: A common site on TBP for transcription by RNA polymerases II and III.
abstract: The TATA-binding protein (TBP) is involved in all nuclear transcription. We show that a common site on TBP is used for transcription initiation complex formation by RNA polymerases (pols) II and III. TBP, the transcription factor IIB (TFIIB)-related factor Brf1 and the pol III-specific factor Bdp1 constitute TFIIIB. A photochemical cross-linking approach was used to survey a collection of human TBP surface residue mutants for their ability to form TFIIIB-DNA complexes reliant on only the TFIIB-related part of Brf1. Mutations impairing complex formation and transcription were identified and mapped on the surface of TBP. The most severe effects were observed for mutations in the C-terminal stirrup of TBP, which is the principal site of interaction between TBP and TFIIB. Structural modeling of the Brf1-TBP complex and comparison with its TFIIB-TBP analog further rationalizes the close resemblance of the TBP interaction with the N-proximal part of Brf1 and TFIIB, and establishes the conserved usage of a TBP surface in pol II and pol III transcription for a conserved function in the initiation of transcription.
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D008969:Molecular Sequence Data; D009154:Mutation; D012319:RNA Polymerase II / Q000378:metabolism*; D012320:RNA Polymerase III / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D035381:TATA-Binding Protein Associated Factors; D035181:TATA-Box Binding Protein / Q000235:genetics / Q000378:metabolism*; D035581:Transcription Factor TFIIB / Q000378:metabolism; D035361:Transcription Factor TFIIIB / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: C090956:BRF1 protein, S cerevisiae; C441028:BRF1 protein, human; D029701:Saccharomyces cerevisiae Proteins; D035381:TATA-Binding Protein Associated Factors; D035181:TATA-Box Binding Protein; D035581:Transcription Factor TFIIB; D035361:Transcription Factor TFIIIB; D012319:RNA Polymerase II; D012320:RNA Polymerase III