Yeast TBP can replace its human homologue in the RNA polymerase I-specific multisubunit factor SL1

• Published in: Journal of molecular biology Vol. 243; no. 5; p. 840
• Main Authors: Rudloff, U, Stunnenberg, H G, Keaveney, M, Grummt, I
• Format: Journal Article
• Language: English
• Published: England 11-11-1994
• Subjects: Blotting, Western; Candida - genetics; Cell Line; DNA-Binding Proteins - genetics; Humans; RNA Polymerase I - genetics; Sequence Homology, Amino Acid; TATA-Box Binding Protein; Transcription Factors - genetics; Transcription, Genetic - genetics; Xenopus Proteins
• ISSN: 0022-2836
• DOI: 10.1006/jmbi.1994.1686

Basic mechanisms of transcription initiation are conserved from yeast to man. However, in contrast to genes transcribed by RNA polymerases II and III, ribosomal gene transcription by RNA polymerase I (Pol I) is species-specific. Promoter selectivity is mediated by SL1/TIF-IB, a multiprotein complex containing the TATA-binding protein (TBP) and TBP-associated factors (TAFs) which bind to DNA and nucleate the assembly of initiation complexes. Using a human cell line that expresses epitope-tagged yeast TBP, we have isolated a chimeric complex consisting of yeast TBP and human TAFs which faithfully promotes human rDNA transcription in vitro. This result argues that specific interactions between TBP and Pol I-specific TAFs have been evolutionarily conserved between distant species. In addition, this finding also underscores the importance of TAFs in determining promoter selectivity of Pol I.