Cryo-electron microscopy: Visualization of the structure of RNA polymerase I while actively transcribing ribosomal DNA genes
November 2016. RNA polymerase is a central enzyme for the cellular function that transcribes DNA to RNA. In their latest paper in Nature, researchers from the BMLS at the Goethe University in Frankfurt and the MPI for Biophysical Chemistry in Göttingen have visualized the RNA Polymerase I (Pol I) while it is actively transcribing ribosome genes in a cellular environment, and have solved its structure with and without nucleic acids at 3.8 Å resolution by cryo-electron microscopy. The structures explain the regulation of transcription elongation in which contracted and expanded polymerase conformations are associated with active and inactive states, respectively. Read more
Figure: On the left a three-dimensional surface rendering of a cryo-electron tomogram showing several successive Pol I enzymes (yellow) transcribing on the DNA (blue), while the emanating RNA (red) with RNA-modifying complexes (cyan) can be seen ending in terminal knobs resembling preribosomal complexes. The DNA and Pol I are zoomed almost a hundred times to reveal the atomic model of the structure of the Pol I shown in a top view on the right. All subunits of the Pol I could be resolved at atomic resolution and are coloured according the standard Pol I subunit colouring: A190, grey; A135, wheat; A49, light blue; A43, slate; AC40, red; A34.5, pink; Rpb5, magenta; Rpb6, silver-blue; AC19, yellow; Rpb8, green; A14, hot pink; A12.2, orange; Rpb10, blue; Rpb12, lemon. Template DNA, non-template DNA and RNA are depicted in medium blue, sky blue and red, respectively.
Prof. Dr. Achilleas Frangakis
Buchmann Institute for Molecular Life Sciences & Institute for Biophysics
Goethe University Frankfurt, Germany
Simon Neyer1*, Michael Kunz2*, Christian Geiss2, Merle Hantsche1, Victor-Valentin Hodirnau2, Anja Seybert2, Christoph Engel1, Margot P. Scheffer2, Patrick Cramer1&, Achilleas S. Frangakis2& (2016). Structure of RNA polymerase I transcribing ribosomal DNA genes. Nature. 2016 Nov 14; DOI 10.1038/nature20561
&shared corresponding authors