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Publication Abstract from PubMed

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.

Structure of the multi-subunit chloroplast RNA polymerase.,do Prado PFV, Ahrens FM, Liebers M, Ditz N, Braun HP, Pfannschmidt T, Hillen HS Mol Cell. 2024 Mar 7;84(5):910-925.e5. doi: 10.1016/j.molcel.2024.02.003. Epub , 2024 Feb 29. PMID:38428434^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.