1m3x

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Revision as of 19:00, 20 November 2007

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spinqualitylabelsall models 1m3x, resolution 2.55Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Photosynthetic Reaction Center From Rhodobacter Sphaeroides

Overview

The structure of the reaction center from Rhodobacter sphaeroides has been, solved by using x-ray diffraction at a 2.55-A resolution limit. Three, lipid molecules that lie on the surface of the protein are resolved in the, electron density maps. In addition to a cardiolipin that has previously, been reported [McAuley, K. E., Fyfe, P. K., Ridge, J. P., Isaacs, N. W., Cogdell, R. J. & Jones, M. R. (1999) Proc. Natl. Acad. Sci. USA 96, 14706-14711], two other major lipids of the cell membrane are found, a, phosphatidylcholine and a glucosylgalactosyl diacylglycerol. The presence, of these three lipids has been confirmed by laser mass spectroscopy. The, lipids are located in the hydrophobic region of the protein surface and, interact predominately with hydrophobic amino acids, in particular, aromatic residues. Although the cardiolipin is over 15 A from the, cofactors, the other two lipids are in close contact with the cofactors, and may contribute to the difference in energetics for the two branches of, cofactors that is primarily responsible for the asymmetry of electron, transfer. The glycolipid is 3.5 A from the active bacteriochlorophyll, monomer and shields this cofactor from the solvent in contrast to a much, greater exposed surface evident for the inactive bacteriochlorophyll, monomer. The phosphate atom of phosphatidylcholine is 6.5 A from the, inactive bacteriopheophytin, and the associated electrostatic interactions, may contribute to electron transfer rates involving this cofactor., Overall, the lipids span a distance of approximately 30 A, which is, consistent with a bilayer-like arrangement suggesting the presence of an, "inner shell" of lipids around membrane proteins that is critical for, membrane function.

About this Structure

1M3X is a Protein complex structure of sequences from Rhodobacter sphaeroides with FE, CL, BCL, BPH, U10, SPO, CDL, PC1 and GGD as ligands. Full crystallographic information is available from OCA.

Reference

Interactions between lipids and bacterial reaction centers determined by protein crystallography., Camara-Artigas A, Brune D, Allen JP, Proc Natl Acad Sci U S A. 2002 Aug 20;99(17):11055-60. Epub 2002 Aug 7. PMID:12167672

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