ジャーナル: Mol Cell / 年: 2024 タイトル: Structure of the multi-subunit chloroplast RNA polymerase. 著者: Paula F V do Prado / Frederik M Ahrens / Monique Liebers / Noah Ditz / Hans-Peter Braun / Thomas Pfannschmidt / Hauke S Hillen / 要旨: 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 ...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.