title: Crystallization and preliminary X-ray diffraction analysis of the light-harvesting protein phycocyanin from the thermophilic cyanobacterium Synechococcus elongatus.
abstract: The crystallization and preliminary crystallographic study of phycocyanin from the thermophilic cyanobacterium Synechococcus elongatus is reported. Phycocyanin is composed of alpha- and beta-subunits consisting of 162 and 172 amino-acid residues, respectively. These associate to form an alphabeta heterodimer, which further associates to give a ring-shaped trimer (alphabeta)(3). Two trimers bind head-to-head to form a hexamer (alphabeta)(6). Phycocyanin crystals have been obtained by the sitting-drop vapour-diffusion method with a precipitant solution containing 30%(w/v) PEG 4000 and 100 mM MES pH 7.5-8.0. Using synchrotron radiation, the crystals diffract to 2.0 A resolution. They belong to the trigonal space group R32, with unit-cell parameters a = b = 186.75 (3), c = 59.75 (4) A, alpha = beta = 90, gamma = 120 degrees. Assuming that the crystallographic triad is identical to the threefold axis of the hexamer and with three (alphabeta)(6) molecules in a unit cell, the calculated molar volume (V(M)) is 2.64 A(3) Da(-1). This value corresponds to a solvent content of approximately 53%, with one alphabeta heterodimer occupying the asymmetric unit.
authors.affiliation: Toray Research Center Inc., 3-3-7 Sonoyama, Otsu, Shiga 520-8567, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Toriumi
authors.forename: S Y
authors.initials: SY
authors.lastname: Park
authors.forename: H
authors.initials: H
authors.lastname: Hashimoto
authors.forename: H
authors.initials: H
authors.lastname: Shimizu
authors.forename: M
authors.initials: M
authors.lastname: Hirano
authors.forename: N
authors.initials: N
authors.lastname: Kamiya
mesh_terms: D003460:Crystallization; D018360:Crystallography, X-Ray; D000458:Cyanobacteria / Q000737:chemistry*; D008027:Light; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry; D010798:Phycocyanin / Q000737:chemistry*; D011487:Protein Conformation
chemical_list: D045322:Photosynthetic Reaction Center Complex Proteins; D010798:Phycocyanin