1L9J

X-Ray Structure of the Cytochrome-c(2)-Photosynthetic Reaction Center Electron Transfer Complex from Rhodobacter sphaeroides in Type I Co-Crystals

Summary for 1L9J

• Entry DOI: 10.2210/pdb1l9j/pdb
• Related: 1AIJ 1CXC 1L9B
• Descriptor: REACTION CENTER PROTEIN L CHAIN, LAURYL DIMETHYLAMINE-N-OXIDE, PROTOPORPHYRIN IX CONTAINING FE, ... (12 entities in total)
• Functional Keywords: bacterial photosynthesis, electron transfer proteins, protein-protein interactions, membrane proteins, protein complexes, photosynthesis
• Biological source: Rhodobacter sphaeroides; More
• Cellular location: Cellular chromatophore membrane; Multi-pass membrane protein: P02954 P02953; Cellular chromatophore membrane; Single-pass membrane protein: P11846; Periplasm: P00095
• Total number of polymer chains: 8
• Total formula weight: 229507.39

Authors

Axelrod, H.L.,Abresch, E.C.,Okamura, M.Y.,Yeh, A.P.,Rees, D.C.,Feher, G. (deposition date: 2002-03-24, release date: 2002-06-12, Last modification date: 2024-10-16)

Primary citation

Axelrod, H.L.,Abresch, E.C.,Okamura, M.Y.,Yeh, A.P.,Rees, D.C.,Feher, G.
X-ray structure determination of the cytochrome c2: reaction center electron transfer complex from Rhodobacter sphaeroides.
J.Mol.Biol., 319:501-515, 2002

PubMed Abstract: In the photosynthetic bacterium Rhodobacter sphaeroides, a water soluble cytochrome c2 (cyt c2) is the electron donor to the reaction center (RC), the membrane-bound pigment-protein complex that is the site of the primary light-induced electron transfer. To determine the interactions important for docking and electron transfer within the transiently bound complex of the two proteins, RC and cyt c2 were co-crystallized in two monoclinic crystal forms. Cyt c2 reduces the photo-oxidized RC donor (D+), a bacteriochlorophyll dimer, in the co-crystals in approximately 0.9 micros, which is the same time as measured in solution. This provides strong evidence that the structure of the complex in the region of electron transfer is the same in the crystal and in solution. X-ray diffraction data were collected from co-crystals to a maximum resolution of 2.40 A and refined to an R-factor of 22% (R(free)=26%). The structure shows the cyt c2 to be positioned at the center of the periplasmic surface of the RC, with the heme edge located above the bacteriochlorophyll dimer. The distance between the closest atoms of the two cofactors is 8.4 A. The side-chain of Tyr L162 makes van der Waals contacts with both cofactors along the shortest intermolecular electron transfer pathway. The binding interface can be divided into two domains: (i) A short-range interaction domain that includes Tyr L162, and groups exhibiting non-polar interactions, hydrogen bonding, and a cation-pi interaction. This domain contributes to the strength and specificity of cyt c2 binding. (ii) A long-range, electrostatic interaction domain that contains solvated complementary charges on the RC and cyt c2. This domain, in addition to contributing to the binding, may help steer the unbound proteins toward the right conformation.

PubMed: 12051924
DOI: 10.1016/S0022-2836(02)00168-7

Experimental method

X-RAY DIFFRACTION (3.25 Å)