CRYSTALLIZATION AND PRELIMINARY-X-RAY ANALYSIS OF TOBACCO RINGSPOT VIRUS

Tobacco ringspot virus, a plant virus that is believed to fill an appa rent niche in the evolution of picornavirus-like capsids, has been cry stallized by vapor diffusion with potassium phosphate and polyethylene glycol buffered at pH 6.5 in a new crystal form. The monoclinic cryst als belong to the space group C2 with unit-cell dimensions of a = 407. 1, b = 399.7, c = 285.9 Angstrom and beta = 129.1 degrees and diffract synchrotron radiation to 3.3 Angstrom. One half of a virus particle c onstitutes the crystallographic asymmetric unit. The orientation of th e virus particle in the unit cell was determined by the rotation funct ion analysis of a partial data set that has been collected at CHESS us ing image plates. Development of a suitable phasing model for the high -resolution structure determination of TRSV with the real-space molecu lar replacement technique is now under way.