Structural basis for the assembly and quinone transport mechanisms of the dimeric photosynthetic RC-LH1 supercomplex

Cao, Peng, Bracun, Laura ORCID: 0000-0001-7698-3718, Yamagata, Atsushi, Christianson, Bern M, Negami, Tatsuki, Zou, Baohua, Terada, Tohru, Canniffe, Daniel P ORCID: 0000-0002-5022-0437, Shirouzu, Mikako, Li, Mei
et al (show 1 more authors) (2022) Structural basis for the assembly and quinone transport mechanisms of the dimeric photosynthetic RC-LH1 supercomplex. NATURE COMMUNICATIONS, 13 (1). 1977-.

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The reaction center (RC) and light-harvesting complex 1 (LH1) form a RC-LH1 core supercomplex that is vital for the primary reactions of photosynthesis in purple phototrophic bacteria. Some species possess the dimeric RC-LH1 complex with a transmembrane polypeptide PufX, representing the largest photosynthetic complex in anoxygenic phototrophs. However, the details of the architecture and assembly mechanism of the RC-LH1 dimer are unclear. Here we report seven cryo-electron microscopy (cryo-EM) structures of RC-LH1 supercomplexes from Rhodobacter sphaeroides. Our structures reveal that two PufX polypeptides are positioned in the center of the S-shaped RC-LH1 dimer, interlocking association between the components and mediating RC-LH1 dimerization. Moreover, we identify another transmembrane peptide, designated PufY, which is located between the RC and LH1 subunits near the LH1 opening. PufY binds a quinone molecule and prevents LH1 subunits from completely encircling the RC, creating a channel for quinone/quinol exchange. Genetic mutagenesis, cryo-EM structures, and computational simulations provide a mechanistic understanding of the assembly and electron transport pathways of the RC-LH1 dimer and elucidate the roles of individual components in ensuring the structural and functional integrity of the photosynthetic supercomplex.

Item Type: Article
Uncontrolled Keywords: Rhodobacter sphaeroides, Benzoquinones, Light-Harvesting Protein Complexes, Photosynthetic Reaction Center Complex Proteins, Peptides, Bacterial Proteins, Cryoelectron Microscopy, Photosynthesis, Models, Molecular
Divisions: Faculty of Health and Life Sciences
Faculty of Health and Life Sciences > Institute of Systems, Molecular and Integrative Biology
Depositing User: Symplectic Admin
Date Deposited: 19 Apr 2022 09:54
Last Modified: 18 Jan 2023 21:05
DOI: 10.1038/s41467-022-29563-3
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