title: Structure of a T = 1 aggregate of alfalfa mosaic virus coat protein seen at 4.5 A resolution.
abstract: A T = 1 empty aggregate of alfalfa mosaic virus coat protein had been crystallized in a hexagonal unit cell and its orientation was determined with the rotation function. A single heavy-atom derivative has now been prepared and the position of the two Hg atoms per protein subunit were determined using a systematic Patterson search procedure, given the particle orientation. Phases, initially determined by single isomorphous replacement, were refined by six cycles of electron density averaging and solvent leveling to produce a 4.5 A resolution electron density map. The protein coat is confined between 95 and 58 A radius. The subunit boundary could be delineated easily. It has a central cavity reminiscent of the beta-barrel in other spherical plant viruses, but its topology could not be determined unambiguously. The spherical particle has large holes at the 5-fold axes, consistent with previous observations. The subunits have substantial interactions at the 2 and 3-fold axes. The structure of the elongated particles is discussed in relation to these results.
mesh_terms: D002213:Capsid; D003460:Crystallization; D000455:Medicago sativa; D008854:Microscopy, Electron; D009029:Mosaic Viruses / Q000648:ultrastructure*; D010663:Phenylmercury Compounds; D011487:Protein Conformation; D014764:Viral Proteins
chemical_list: D010663:Phenylmercury Compounds; D014764:Viral Proteins; C002910:4-hydroxymercuribenzenesulfonate