Functional architecture of RNA polymerase I.

Synthesis of ribosomal RNA (rRNA) by RNA polymerase (Pol) I is the first step in ribosome biogenesis and a regulatory switch in eukaryotic cell growth. Here we report the 12 A cryo-electron microscopic structure for the complete 14-subunit yeast Pol I, a homology model for the core enzyme, and the ...
crystal structure of the subcomplex A14/43. In the resulting hybrid structure of Pol I, A14/43, the clamp, and the dock domain contribute to a unique surface interacting with promoter-specific initiation factors. The Pol I-specific subunits A49 and A34.5 form a heterodimer near the enzyme funnel that acts as a built-in elongation factor and is related to the Pol II-associated factor TFIIF. In contrast to Pol II, Pol I has a strong intrinsic 3'-RNA cleavage activity, which requires the C-terminal domain of subunit A12.2 and, apparently, enables ribosomal RNA proofreading and 3'-end trimming.
Mesh Terms:
Binding Sites, Cryoelectron Microscopy, Crystallography, X-Ray, DNA Polymerase I, Models, Molecular, Mutation, Peptide Elongation Factors, Peptide Initiation Factors, Promoter Regions, Genetic, Protein Conformation, Protein Interaction Domains and Motifs, Protein Interaction Mapping, Protein Structure, Tertiary, Protein Subunits, RNA Processing, Post-Transcriptional, RNA, Ribosomal, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Structure-Activity Relationship, Transcription Factors, TFII, Transcription, Genetic, Transcriptional Elongation Factors
Cell
Date: Dec. 28, 2007
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