title: Lipidic cubic phase crystal structure of the photosynthetic reaction centre from Rhodobacter sphaeroides at 2.35A resolution.
abstract: Well-ordered crystals of the bacterial photosynthetic reaction centre from Rhodobacter sphaeroides were grown from a lipidic cubic phase. Here, we report the type I crystal packing that results from this crystallisation medium, for which 3D crystals grow as stacked 2D crystals, and the reaction centre X-ray structure is refined to 2.35A resolution. In this crystal form, the location of the membrane bilayer could be assigned with confidence. A cardiolipin-binding site is found at the protein-protein interface within the membrane-spanning region, shedding light on the formation of crystal contacts within the membrane. A chloride-binding site was identified in the membrane-spanning region, which suggests a putative site for interaction with the light-harvesting complex I, the cytochrome bc(1) complex or PufX. Comparisons with the X-ray structures of this reaction centre deriving from detergent-based crystals are drawn, indicating that a slight compression occurs in this lipid-rich environment.
authors.affiliation: Department of Molecular Biotechnology, Chalmers University of Technology, P.O. Box 462, SE-405 30 Gothenburg, Sweden.
authors.forename: Gergely
authors.initials: G
authors.lastname: Katona
authors.forename: Ulf
authors.initials: U
authors.lastname: Andréasson
authors.forename: Ehud M
authors.initials: EM
authors.lastname: Landau
authors.forename: Lars-Erik
authors.initials: LE
authors.lastname: Andréasson
authors.forename: Richard
authors.initials: R
authors.lastname: Neutze
mesh_terms: D001665:Binding Sites; D002308:Cardiolipins / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D003460:Crystallization; D018360:Crystallography, X-Ray; D003902:Detergents; D008051:Lipid Bilayers / Q000378:metabolism; D050356:Lipid Metabolism; D008055:Lipids / Q000737:chemistry*; D008958:Models, Molecular; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation; D012242:Rhodobacter sphaeroides / Q000737:chemistry*
chemical_list: D002308:Cardiolipins; D002712:Chlorides; D003902:Detergents; D008051:Lipid Bilayers; D008055:Lipids; D045322:Photosynthetic Reaction Center Complex Proteins