5m5x
RNA Polymerase I elongation complex 1
Structural highlights
FunctionRPAC1_YEAST DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. Common component of RNA polymerases I and III which synthesize ribosomal RNA precursors and small RNAs, such as 5S rRNA and tRNAs, respectively. RPAC1 is part of the Pol core element with the central large cleft and probably a clamp element that moves to open and close the cleft (By similarity). Publication Abstract from PubMedRNA polymerase I (Pol I) is a 14-subunit enzyme that solely synthesizes pre-ribosomal RNA. Recently, the crystal structure of apo Pol I gave unprecedented insight into its molecular architecture. Here, we present three cryo-EM structures of elongating Pol I, two at 4.0 A and one at 4.6 A resolution, and a Pol I open complex at 3.8 A resolution. Two modules in Pol I mediate the narrowing of the DNA-binding cleft by closing the clamp domain. The DNA is bound by the clamp head and by the protrusion domain, allowing visualization of the upstream and downstream DNA duplexes in one of the elongation complexes. During formation of the Pol I elongation complex, the bridge helix progressively folds, while the A12.2 C-terminal domain is displaced from the active site. Our results reveal the conformational changes associated with elongation complex formation and provide additional insight into the Pol I transcription cycle. Molecular Structures of Transcribing RNA Polymerase I.,Tafur L, Sadian Y, Hoffmann NA, Jakobi AJ, Wetzel R, Hagen WJ, Sachse C, Muller CW Mol Cell. 2016 Nov 16. pii: S1097-2765(16)30721-3. doi:, 10.1016/j.molcel.2016.11.013. PMID:27867008[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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