Structural Basis of RNA Polymerase I Transcription Initiation.
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.
Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
Christoph
C
Engel
Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
Tobias
T
Gubbey
Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
Simon
S
Neyer
Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
Sarah
S
Sainsbury
Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
Christiane
C
Oberthuer
Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
Carlo
C
Baejen
Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
Carrie
C
Bernecky
Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany. Electronic address: patrick.cramer@mpibpc.mpg.de.
Patrick
P
Cramer
D020285:Cryoelectron Microscopy; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D046912:Multiprotein Complexes / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D011401:Promoter Regions, Genetic; D012318:RNA Polymerase I / Q000737:chemistry; D012441:Saccharomyces cerevisiae / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D061785:Transcription Initiation, Genetic; D014158:Transcription, Genetic
D046912:Multiprotein Complexes; D029701:Saccharomyces cerevisiae Proteins; D012318:RNA Polymerase I
RNA polymerase I; X-ray crystallography; core factor; cryo-EM; ribosomal RNA promoter; transcription initiation