Details

Autor(en) / Beteiligte

• Cao, Peng
• Bracun, Laura
• Yamagata, Atsushi
• Christianson, Bern M
• Negami, Tatsuki
• Zou, Baohua
• Terada, Tohru
• Canniffe, Daniel P
• Shirouzu, Mikako
• Li, Mei
• Liu, Lu-Ning

Titel

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

Ist Teil von

• Nature communications, 2022-04, Vol.13 (1), p.1977-1977, Article 1977

Ort / Verlag

England: Nature Publishing Group

Erscheinungsjahr

2022

Link zum Volltext

Quelle

MEDLINE

Beschreibungen/Notizen

• 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.