Molecular Cell
Volume 39, Issue 4, 27 August 2010, Pages 583-594
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Article
RNA Polymerase I Contains a TFIIF-Related DNA-Binding Subcomplex

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Summary

The eukaryotic RNA polymerases Pol I, II, and III use different promoters to transcribe different classes of genes. Promoter usage relies on initiation factors, including TFIIF and TFIIE, in the case of Pol II. Here, we show that the Pol I-specific subunits A49 and A34.5 form a subcomplex that binds DNA and is related to TFIIF and TFIIE. The N-terminal regions of A49 and A34.5 form a dimerization module that stimulates polymerase-intrinsic RNA cleavage and has a fold that resembles the TFIIF core. The C-terminal region of A49 forms a “tandem winged helix” (tWH) domain that binds DNA with a preference for the upstream promoter nontemplate strand and is predicted in TFIIE. Similar domains are predicted in Pol III-specific subunits. Thus, Pol I/III subunits that have no counterparts in Pol II are evolutionarily related to Pol II initiation factors and may have evolved to mediate promoter specificity and transcription processivity.

Highlights

► RNA polymerase I subcomplex A49/34.5 consists of two flexibly linked domains ► A49/34.5 forms a dimerization domain similar to TFIIF that stimulates RNA cleavage ► A49 contains a tandem winged helix domain that binds DNA and may exist in TFIIE ► Pol III contains TFIIE/F-related subunits that may mediate promoter specificity

DNA
RNA

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