STRUCTURE DETERMINATION OF COXSACKIEVIRUS B3 TO 3.5 ANGSTROM RESOLUTION

The crystal structure of coxsackievirus B3 (CVB3) has been determined to 3.5 Angstrom resolution. The icosahedral CVB3 particles crystallize in the monoclinic space group, P2(1), (a = 574.6, b = 302.1, c = 521.6 Angstrom, beta=107.7 degrees) with two virions in the asymmetric unit giving 120-fold non-crystallographic redundancy. The crystals diffracted to 2.7 Angstrom resolution and the X-ray data set was 55% complete to 3.0 Angstrom resolution. Systematically weak reflections and the self-rotation function established pseudo R32 symmetry with each particle sitting on a 32 special position. This constrained the orientation and position of each particle in the monoclinic cell to near face-centered positions and allowed for a total of six possible monoclinic space-group settings. Correct interpretation of the high resolution (3.0-3.2 Angstrom) self-rotation function was instrumental in determining the deviations from R32 orientations of the virus particles in the unit cell. Accurate particle orientations permitted the correct assignment of the crystal space-group setting amongst the six ambiguous possibilities and for the correct determination of particle positions. Real-space electron-density averaging and phase refinement, using human rhinovius 14 (HRV14) as an initial phasing model, have been carried out to 3.5 Angstrom resolution. The initial structural model has been built and refined to 3.5 Angstrom resolution using X-PLOR.