title: Molecular structures of unbound and transcribing RNA polymerase III.
abstract: Transcription of genes encoding small structured RNAs such as transfer RNAs, spliceosomal U6 small nuclear RNA and ribosomal 5S RNA is carried out by RNA polymerase III (Pol III), the largest yet structurally least characterized eukaryotic RNA polymerase. Here we present the cryo-electron microscopy structures of the Saccharomyces cerevisiae Pol III elongating complex at 3.9 Å resolution and the apo Pol III enzyme in two different conformations at 4.6 and 4.7 Å resolution, respectively, which allow the building of a 17-subunit atomic model of Pol III. The reconstructions reveal the precise orientation of the C82-C34-C31 heterotrimer in close proximity to the stalk. The C53-C37 heterodimer positions residues involved in transcription termination close to the non-template DNA strand. In the apo Pol III structures, the stalk adopts different orientations coupled with closed and open conformations of the clamp. Our results provide novel insights into Pol III-specific transcription and the adaptation of Pol III towards its small transcriptional targets.
authors.affiliation: European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
authors.forename: Niklas A
authors.initials: NA
authors.lastname: Hoffmann
authors.affiliation: European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany.|European Molecular Biology Laboratory (EMBL), Hamburg Unit, Notkestrasse 85, 22607 Hamburg, Germany.
authors.forename: Arjen J
authors.initials: AJ
authors.lastname: Jakobi
authors.affiliation: European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
authors.forename: María
authors.initials: M
authors.lastname: Moreno-Morcillo
authors.affiliation: European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Glatt
authors.affiliation: European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Kosinski
authors.affiliation: European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
authors.forename: Wim J H
authors.initials: WJ
authors.lastname: Hagen
authors.affiliation: European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Sachse
authors.affiliation: European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
authors.forename: Christoph W
authors.initials: CW
authors.lastname: Müller
mesh_terms: D020285:Cryoelectron Microscopy; D008958:Models, Molecular; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012320:RNA Polymerase III / Q000737:chemistry*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry*
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D012320:RNA Polymerase III