부산대학교 도서관

To access, purchase, authenticate, or subscribe to the full-text of this article, please visit this link: http://dx.doi.org/10.1016/j.cell.2017.03.003 Byline: Christoph Engel (1,2), Tobias Gubbey (1,2), Simon Neyer (1,2), Sarah Sainsbury (1), Christiane Oberthuer (1), Carlo Baejen (1), Carrie Bernecky (1), Patrick Cramer [patrick.cramer@mpibpc.mpg.de] (1,3,*) Keywords transcription initiation; RNA polymerase I; ribosomal RNA promoter; core factor; cryo-EM; X-ray crystallography Highlights * RNA polymerase I initiation factor 'core factor' has a bi-modular structure * Core factor can bind Pol I via three interfaces in two different locations * Architecture of initially transcribing Pol I complex elucidated by cryo-EM * Local pliability of rDNA may define promoters rather than sequence Summary Transcription 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. Author Affiliation: (1) Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Gottingen, Germany * Corresponding author Article History: Received 7 December 2016; Revised 16 February 2017; Accepted 1 March 2017 (miscellaneous) Published: March 23, 2017 (footnote)2 Co-first author (footnote)3 Lead Contact