5n5z
From Proteopedia
Cryo-EM structure of RNA polymerase I in complex with Rrn3 and Core Factor (Orientation II)
Structural highlights
FunctionRRN6_YEAST Acts as component of the core factor (CF) complex which is essential for the initiation of rDNA transcription by RNA polymerase I. After binding of UAF (upstream activation factor) to an upstream element of the promoter, CF is recruited in a SPT15/TBP-dependent manner to form a preinitiation complex.[1] 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[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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