1pcr

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spinqualitylabelsall models 1pcr, resolution 2.65Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

STRUCTURE OF THE PHOTOSYNTHETIC REACTION CENTRE FROM RHODOBACTER SPHAEROIDES AT 2.65 ANGSTROMS RESOLUTION: COFACTORS AND PROTEIN-COFACTOR INTERACTIONS

Overview

BACKGROUND: Photosynthetic reaction centres (RCs) catalyze light-driven, electron, transport across photosynthetic membranes. The photosynthetic, bacterium Rhodobacter, sphaeroides is often used for studies of RCs, and, three groups have determined the structure of its reaction centre. There, are discrepancies between these structures, however, and to resolve these, we have determined the structure to higher resolution than before, using a, new crystal form. RESULTS: The new structure provides a more detailed, description of the Rb. sphaeroides RC, and allows us to compare it with, the structure of the RC from Rhodopseudomonas viridis. We find no evidence, to support most of the published differences in cofactor binding between, the RCs from Rps. viridis and Rb. sphaeroides. Generally, the mode of, cofactor binding is conserved, particularly along the electron transfer, pathway. Substantial differences are only found at ring V of one, bacteriochlorophyll of the 'special pair' and for the secondary quinone, QB. A water chain with a length of about 23 A including 14 water molecules, extends from the QB to the cytoplasmic side of the RC. CONCLUSIONS: The, cofactor arrangement and the mode of binding to the protein seem to be, very similar among the non-sulphur bacterial photosynthetic RCs. The, functional role of the displaced QB molecule, which might be present as, quinol, rather than quinone, is not yet clear. The newly discovered water, chain to the QB binding site suggests a pathway for the protonation of the, secondary quinone QB.

About this Structure

1PCR is a Protein complex structure of sequences from Rhodobacter sphaeroides with FE, PO4, BCL, BPH, U10, SPO and LDA as ligands. Full crystallographic information is available from OCA.

Reference

Structure of the photosynthetic reaction centre from Rhodobacter sphaeroides at 2.65 A resolution: cofactors and protein-cofactor interactions., Ermler U, Fritzsch G, Buchanan SK, Michel H, Structure. 1994 Oct 15;2(10):925-36. PMID:7866744

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