Structure of the multi-subunit chloroplast RNA polymerase

authored by
Paula F V do Prado, Frederik M Ahrens, Monique Liebers, Noah Ditz, Hans-Peter Braun, Thomas Pfannschmidt, Hauke Hillen
Abstract

Chloroplasts contain a dedicated genome that encodes subunits of the photosynthesis machinery. Transcription of photosynthesis genes is predominantly carried out by a plastid-encoded RNA polymerase (PEP), a nearly 1 MDa complex composed of core subunits with homology to eubacterial RNA polymerases (RNAPs) and at least 12 additional chloroplast-specific PEP-associated proteins (PAPs). However, the architecture of this complex and the functions of the PAPs remain unknown. Here, we report the cryo-EM structure of a 19-subunit PEP complex from Sinapis alba (white mustard). The structure reveals that the PEP core resembles prokaryotic and nuclear RNAPs but contains chloroplast-specific features that mediate interactions with the PAPs. The PAPs are unrelated to known transcription factors and arrange around the core in a unique fashion. Their structures suggest potential functions during transcription in the chemical environment of chloroplasts. These results reveal structural insights into chloroplast transcription and provide a framework for understanding photosynthesis gene expression.

Organisation(s)
Institute of Botany
Section Plant Physiology
Institute of Plant Genetics
Section Plant Molecular Biology and Plant Proteomics
External Organisation(s)
University of Göttingen
Universitätsmedizin Göttingen (UMG)
Type
Article
Journal
Molecular cell
Volume
84
Pages
910-925.e5
ISSN
1097-2765
Publication date
07.03.2024
Publication status
Published
Peer reviewed
Yes
ASJC Scopus subject areas
Molecular Biology, Cell Biology
Electronic version(s)
https://doi.org/10.1016/j.molcel.2024.02.003 (Access: Open)