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.
Publication types
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Research Support, N.I.H., Extramural
MeSH terms
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Amino Acid Sequence
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Amino Acid Substitution
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Humans
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Molecular Sequence Data
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Pol1 Transcription Initiation Complex Proteins / chemistry*
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Pol1 Transcription Initiation Complex Proteins / genetics
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Pol1 Transcription Initiation Complex Proteins / metabolism*
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Protein Folding
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Protein Interaction Domains and Motifs
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Protein Structure, Secondary
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Protein Structure, Tertiary
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RNA Polymerase I / metabolism*
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Saccharomyces cerevisiae Proteins / chemistry*
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Saccharomyces cerevisiae Proteins / genetics
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Saccharomyces cerevisiae Proteins / metabolism*
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Sequence Alignment
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TATA-Box Binding Protein / metabolism
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Transcription Factor TFIIB / chemistry
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Transcription Factor TFIIB / metabolism
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Transcription Factor TFIIIB / chemistry
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Transcription Factor TFIIIB / genetics
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Transcription Factor TFIIIB / metabolism
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Transcription, Genetic
Substances
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BRF1 protein, S cerevisiae
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Pol1 Transcription Initiation Complex Proteins
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RRN7 protein, S cerevisiae
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Saccharomyces cerevisiae Proteins
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TAF1B protein, human
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TATA-Box Binding Protein
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Transcription Factor TFIIB
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Transcription Factor TFIIIB
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RNA Polymerase I