Cryo-EM structure of the Blastochloris viridis LH1-RC complex at 2.9 angstrom

Qian, Pu, Siebert, C Alistair, Wang, Peiyi, Canniffe, Daniel P ORCID: 0000-0002-5022-0437 and Hunter, C Neil
(2018) Cryo-EM structure of the Blastochloris viridis LH1-RC complex at 2.9 angstrom. NATURE, 556 (7700). pp. 203-208.

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The light-harvesting 1–reaction centre (LH1–RC) complex is a key functional component of bacterial photosynthesis. Here we present a 2.9 Å resolution cryo-electron microscopy structure of the bacteriochlorophyll b-based LH1–RC complex from Blastochloris viridis that reveals the structural basis for absorption of infrared light and the molecular mechanism of quinone migration across the LH1 complex. The triple-ring LH1 complex comprises a circular array of 17 β-polypeptides sandwiched between 17 α- and 16 γ-polypeptides. Tight packing of the γ-apoproteins between β-polypeptides collectively interlocks and stabilizes the LH1 structure; this, together with the short Mg–Mg distances of bacteriochlorophyll b pairs, contributes to the large redshift of bacteriochlorophyll b absorption. The ‘missing’ 17th γ-polypeptide creates a pore in the LH1 ring, and an adjacent binding pocket provides a folding template for a quinone, Q P, which adopts a compact, export-ready conformation before passage through the pore and eventual diffusion to the cytochrome bc 1 complex.

Item Type: Article
Uncontrolled Keywords: Hyphomicrobiaceae, Magnesium, Benzoquinones, Bacteriochlorophylls, Light-Harvesting Protein Complexes, Apoproteins, Bacterial Proteins, Cryoelectron Microscopy, Photosynthesis, Binding Sites, Protein Conformation, Models, Molecular, Protein Stability
Depositing User: Symplectic Admin
Date Deposited: 08 May 2019 09:11
Last Modified: 19 Jan 2023 01:05
DOI: 10.1038/s41586-018-0014-5
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