title: The refined crystal structure of cowpea mosaic virus at 2.8 A resolution.
abstract: Comoviruses are a group of plant viruses in the picornavirus superfamily. The type member of comoviruses, cowpea mosaic virus (CPMV), was crystallized in the cubic space group I23, a = 317 A and the hexagonal space group P6(1)22, a = 451 A, c = 1038 A. Structures of three closely similar nucleoprotein particles were determined in the cubic form. The roughly 300-A capsid was similar to the picornavirus capsid displaying a pseudo T = 3 (P = 3) surface lattice. The three beta-sandwich domains adopt two orientations, one with the long axis radial and the other two with the long axes tangential in reference to the capsid sphere. T = 3 viruses display one or the other of these two orientations. The CPMV capsid was permeable to cesium ions, leading to a disturbance of the beta-annulus inside a channel-like structure, suggesting an ion channel. The hexagonal crystal form diffracted X rays to 3 A resolution, despite the large unit cell. The large ( approximately 200 A) solvent channels in the lattice allow exchange of CPMV cognate Fab fragments. As an initial step in the structure determination of the CPMV/Fab complex, the P6(1)22 crystal structure was solved by molecular replacement with the CPMV model determined in the cubic cell.
authors.affiliation: Department of Molecular Biology, MB-31, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California, 92037, USA.
authors.forename: T
authors.initials: T
authors.lastname: Lin
authors.forename: Z
authors.initials: Z
authors.lastname: Chen
authors.forename: R
authors.initials: R
authors.lastname: Usha
authors.forename: C V
authors.initials: CV
authors.lastname: Stauffacher
authors.forename: J B
authors.initials: JB
authors.lastname: Dai
authors.forename: T
authors.initials: T
authors.lastname: Schmidt
authors.forename: J E
authors.initials: JE
authors.lastname: Johnson
mesh_terms: D000595:Amino Acid Sequence; D000914:Antibodies, Viral / Q000648:ultrastructure; D000936:Antigen-Antibody Complex / Q000648:ultrastructure; D002213:Capsid / Q000648:ultrastructure; D017798:Comovirus / Q000648:ultrastructure*; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D012367:RNA, Viral / Q000648:ultrastructure; D014764:Viral Proteins / Q000648:ultrastructure
chemical_list: D000914:Antibodies, Viral; D000936:Antigen-Antibody Complex; D012367:RNA, Viral; D014764:Viral Proteins