7PQD

Cryo-EM structure of the dimeric Rhodobacter sphaeroides RC-LH1 core complex at 2.9 A: the structural basis for dimerisation

This is a non-PDB format compatible entry.

Summary for 7PQD

• Entry DOI: 10.2210/pdb7pqd/pdb
• EMDB information: 13590
• Descriptor: LH1-alpha, 3,4-DIHYDROSPHEROIDENE, 1,2-Distearoyl-sn-glycerophosphoethanolamine, ... (19 entities in total)
• Functional Keywords: light harvesting complex, photosynthesis, cryo-em, purple bacteria, rc-lh1, rc-lh1-pufxyz, dimer, dimeric core complex
• Biological source: Cereibacter sphaeroides 2.4.1; More
• Total number of polymer chains: 70
• Total formula weight: 676530.93

Authors

Qian, P.,Hunter, C.N. (deposition date: 2021-09-17, release date: 2021-11-24, Last modification date: 2024-11-13)

Primary citation

Qian, P.,Croll, T.I.,Hitchcock, A.,Jackson, P.J.,Salisbury, J.H.,Castro-Hartmann, P.,Sader, K.,Swainsbury, D.J.K.,Hunter, C.N.
Cryo-EM structure of the dimeric Rhodobacter sphaeroides RC-LH1 core complex at 2.9 angstrom : the structural basis for dimerisation.
Biochem.J., 478:3923-3937, 2021

PubMed Abstract: The dimeric reaction centre light-harvesting 1 (RC-LH1) core complex of Rhodobacter sphaeroides converts absorbed light energy to a charge separation, and then it reduces a quinone electron and proton acceptor to a quinol. The angle between the two monomers imposes a bent configuration on the dimer complex, which exerts a major influence on the curvature of the membrane vesicles, known as chromatophores, where the light-driven photosynthetic reactions take place. To investigate the dimerisation interface between two RC-LH1 monomers, we determined the cryogenic electron microscopy structure of the dimeric complex at 2.9 Å resolution. The structure shows that each monomer consists of a central RC partly enclosed by a 14-subunit LH1 ring held in an open state by PufX and protein-Y polypeptides, thus enabling quinones to enter and leave the complex. Two monomers are brought together through N-terminal interactions between PufX polypeptides on the cytoplasmic side of the complex, augmented by two novel transmembrane polypeptides, designated protein-Z, that bind to the outer faces of the two central LH1 β polypeptides. The precise fit at the dimer interface, enabled by PufX and protein-Z, by C-terminal interactions between opposing LH1 αβ subunits, and by a series of interactions with a bound sulfoquinovosyl diacylglycerol lipid, bring together each monomer creating an S-shaped array of 28 bacteriochlorophylls. The seamless join between the two sets of LH1 bacteriochlorophylls provides a path for excitation energy absorbed by one half of the complex to migrate across the dimer interface to the other half.

PubMed: 34622934
DOI: 10.1042/BCJ20210696

Experimental method

ELECTRON MICROSCOPY (2.9 Å)