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Proc Natl Acad Sci U S A. 2003 Jun 10;100(12):6964-8. Epub 2003 May 13.

Architecture of initiation-competent 12-subunit RNA polymerase II.

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  • 1Institute of Biochemistry and Gene Center, University of Munich, Feodor-Lynen-Strasse 25, 81377 Munich, Germany.

Abstract

RNA polymerase (Pol) II consists of a 10-polypeptide catalytic core and the two-subunit Rpb4/7 complex that is required for transcription initiation. Previous structures of the Pol II core revealed a "clamp," which binds the DNA template strand via three "switch regions," and a flexible "linker" to the C-terminal repeat domain (CTD). Here we derived a model of the complete Pol II by fitting structures of the core and Rpb4/7 to a 4.2-A crystallographic electron density map. Rpb4/7 protrudes from the polymerase "upstream face," on which initiation factors assemble for promoter DNA loading. Rpb7 forms a wedge between the clamp and the linker, restricting the clamp to a closed position. The wedge allosterically prevents entry of the promoter DNA duplex into the active center cleft and induces in two switch regions a conformation poised for template-strand binding. Interaction of Rpb4/7 with the linker explains Rpb4-mediated recruitment of the CTD phosphatase to the CTD during Pol II recycling. The core-Rpb7 interaction and some functions of Rpb4/7 are apparently conserved in all eukaryotic and archaeal RNA polymerases but not in the bacterial enzyme.

Comment in

  • RNA polymerase II at initiation. [Proc Natl Acad Sci U S A. 2003]
PMID:
12746495
[PubMed - indexed for MEDLINE]
PMCID:
PMC165813
Free PMC Article

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