4V9G

RC-LH1-PufX dimer complex from Rhodobacter sphaeroides

This is a non-PDB format compatible entry.

Summary for 4V9G

• Entry DOI: 10.2210/pdb4v9g/pdb
• Descriptor: Light-harvesting protein B-875 alpha chain, PHOSPHATE ION, FE (II) ION, ... (12 entities in total)
• Functional Keywords: photosynthesis, antenna complex lh1, reaction centre, chromophores, photosynthetic complexes, photosynthetic light capture and electron transfer, photosynthetic chromophores, membrane spherical vesicles, pufx, quinol, quinone
• Biological source: Rhodobacter sphaeroides; More
• Cellular location: Cell inner membrane; Single-pass type II membrane protein: P0C0X9 P13402; Cell membrane : Q3J1A3; Cellular chromatophore membrane; Single-pass membrane protein: P0C0Y7; Cellular chromatophore membrane; Multi-pass membrane protein: P0C0Y8 P0C0Y9
• Total number of polymer chains: 64
• Total formula weight: 619063.11

Authors

Qian, P.,Papiz, M.Z.,Jackson, P.J.,Brindley, A.A.,Ng, I.W.,Olsen, J.D.,Dickman, M.J.,Bullough, P.A.,Hunter, C.N. (deposition date: 2013-02-21, release date: 2014-07-09, Last modification date: 2024-02-28)

Primary citation

Qian, P.,Papiz, M.Z.,Jackson, P.J.,Brindley, A.A.,Ng, I.W.,Olsen, J.D.,Dickman, M.J.,Bullough, P.A.,Hunter, C.N.
Three-Dimensional Structure of the Rhodobacter sphaeroides RC-LH1-PufX Complex: Dimerization and Quinone Channels Promoted by PufX.
Biochemistry, 52:7575-7585, 2013

PubMed Abstract: Reaction center-light harvesting 1 (RC-LH1) complexes are the fundamental units of bacterial photosynthesis, which use solar energy to power the reduction of quinone to quinol prior to the formation of the proton gradient that drives ATP synthesis. The dimeric RC-LH1-PufX complex of Rhodobacter sphaeroides is composed of 64 polypeptides and 128 cofactors, including 56 LH1 bacteriochlorophyll a (BChl a) molecules that surround and donate energy to the two RCs. The 3D structure was determined to 8 Å by X-ray crystallography, and a model was built with constraints provided by electron microscopy (EM), nuclear magnetic resonance (NMR), mass spectrometry (MS), and site-directed mutagenesis. Each half of the dimer complex consists of a RC surrounded by an array of 14 LH1 αβ subunits, with two BChls sandwiched between each αβ pair of transmembrane helices. The N- and C-terminal extrinsic domains of PufX promote dimerization by interacting with the corresponding domains of an LH1 β polypeptide from the other half of the RC-LH1-PufX complex. Close contacts between PufX, an LH1 αβ subunit, and the cytoplasmic domain of the RC-H subunit prevent the LH1 complex from encircling the RC and create a channel connecting the RC QB site to an opening in the LH1 ring, allowing Q/QH₂ exchange with the external quinone pool. We also identified a channel that connects the two halves of the dimer, potentially forming a long-range pathway for quinone migration along rows of RC-LH1-PufX complexes in the membrane. The structure of the RC-LH1-PufX complex explains the crucial role played by PufX in dimer formation, and it shows how quinone traffic traverses the LH1 complex as it shuttles between the RC and the cytochrome bc₁ complex.

PubMed: 24131108
DOI: 10.1021/bi4011946

Experimental method

X-RAY DIFFRACTION (7.78 Å)