5n5y
From Proteopedia
Cryo-EM structure of RNA polymerase I in complex with Rrn3 and Core Factor (Orientation III)
Structural highlights
FunctionRPA2_YEAST DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. Second largest core component of RNA polymerase I which synthesizes ribosomal RNA precursors. Proposed to contribute to the polymerase catalytic activity and forms the polymerase active center together with the largest subunit. Pol I is composed of mobile elements and RPA2 is part of the 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 PubMedTranscription initiation at the ribosomal RNA promoter requires RNA polymerase (Pol) I and the initiation factors Rrn3 and core factor (CF). Here, we combine X-ray crystallography and cryo-electron microscopy (cryo-EM) to obtain a molecular model for basal Pol I initiation. The three-subunit CF binds upstream promoter DNA, docks to the Pol I-Rrn3 complex, and loads DNA into the expanded active center cleft of the polymerase. DNA unwinding between the Pol I protrusion and clamp domains enables cleft contraction, resulting in an active Pol I conformation and RNA synthesis. Comparison with the Pol II system suggests that promoter specificity relies on a distinct "bendability" and "meltability" of the promoter sequence that enables contacts between initiation factors, DNA, and polymerase. Structural Basis of RNA Polymerase I Transcription Initiation.,Engel C, Gubbey T, Neyer S, Sainsbury S, Oberthuer C, Baejen C, Bernecky C, Cramer P Cell. 2017 Mar 23;169(1):120-131.e22. doi: 10.1016/j.cell.2017.03.003. PMID:28340337[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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