EMD-32062

Single-particle
4.2 Å
EMD-32062 Deposition: 15/10/2021
Map released: 04/05/2022
Last modified: 19/06/2024
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links

EMD-32062

Rba sphaeroides PufX-KO RC-LH1

EMD-32062

Single-particle
4.2 Å
EMD-32062 Deposition: 15/10/2021
Map released: 04/05/2022
Last modified: 19/06/2024
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Sample Organism: Cereibacter sphaeroides 2.4.1
Sample: Rhodobacter sphaeroides PufX-KO RC-LH1
Fitted models: 7voy (Avg. Q-score: 0.372)

Deposition Authors: Bracun L , Yamagata A
Structural basis for the assembly and quinone transport mechanisms of the dimeric photosynthetic RC-LH1 supercomplex.
Cao P, Bracun L , Yamagata A , Christianson BM, Negami T, Zou B, Terada T , Canniffe DP , Shirouzu M , Li M , Liu LN
(2022) Nat Commun , 13 , 1977 - 1977
PUBMED: 35418573
DOI: doi:10.1038/s41467-022-29563-3
ISSN: 2041-1723
Abstract:
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.