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Cryo-EM structure of the Blastochloris viridis LH1–RC complex at 2.9 Å
DOI:
10.1038/s41586-018-0014-5
Authors:
Pu
Qian
(University of Sheffield)
,
C. Alistair
Siebert
(Diamond Light Source)
,
Peiyi
Wang
(University of Leeds)
,
Daniel P.
Canniffe
(University of Sheffield)
,
C. Neil
Hunter
(University of Sheffield)
Co-authored by industrial partner:
No
Type:
Journal Paper
Journal:
Nature
, VOL 103
State:
Published (Approved)
Published:
April 2018
Diamond Proposal Number(s):
13888
Abstract: 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.
Journal Keywords: Antenna complex; Cryoelectron microscopy
Subject Areas:
Biology and Bio-materials
Diamond Offline Facilities:
Electron Bio-Imaging Centre (eBIC)
Instruments:
Krios I-Titan Krios I at Diamond
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