TY - JOUR TI - The cryo-EM structure of a 12-subunit variant of RNA polymerase I reveals dissociation of the A49-A34.5 heterodimer and rearrangement of subunit A12.2 AU - Tafur, Lucas AU - Sadian, Yashar AU - Hanske, Jonas AU - Wetzel, Rene AU - Weis, Felix AU - Müller, Christoph W A2 - Kuriyan, John A2 - Wolberger, Cynthia A2 - Vannini, Alessandro VL - 8 PY - 2019 DA - 2019/03/26 SP - e43204 C1 - eLife 2019;8:e43204 DO - 10.7554/eLife.43204 UR - https://doi.org/10.7554/eLife.43204 AB - RNA polymerase (Pol) I is a 14-subunit enzyme that solely transcribes pre-ribosomal RNA. Cryo-electron microscopy (EM) structures of Pol I initiation and elongation complexes have given first insights into the molecular mechanisms of Pol I transcription. Here, we present cryo-EM structures of yeast Pol I elongation complexes (ECs) bound to the nucleotide analog GMPCPP at 3.2 to 3.4 Å resolution that provide additional insight into the functional interplay between the Pol I-specific transcription-like factors A49-A34.5 and A12.2. Strikingly, most of the nucleotide-bound ECs lack the A49-A34.5 heterodimer and adopt a Pol II-like conformation, in which the A12.2 C-terminal domain is bound in a previously unobserved position at the A135 surface. Our structural and biochemical data suggest a mechanism where reversible binding of the A49-A34.5 heterodimer could contribute to the regulation of Pol I transcription initiation and elongation. KW - RNA polymerase I KW - transcription regulation KW - elongation complex KW - ribosomal RNA synthesis JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -