W0401

Virus Crystallography: Phase and Function with X-ray Diffraction and cryoEM Data. John Johnson, Molecular Biology, The Scripps Research Institute, 10550 N. Torrey Pines Rd, La Jolla, CA 92129, USA.

Crystallographic studies of icosahedral viruses benefit from the structural redundancy present in the crystalline particles. Numerous virus structures have been solved with a phasing model at low resolution, based on cryoEM and image reconstruction, combined with real space averaging of electron density and incremental phase extension to high resolution. The method is most powerful when there is significant overlap between the resolution of the cryoEM model (usually 1000-20Å) and the x-ray data. Here we discuss the collection and phase determination of single crystal and solution x-ray data between 200 and 20Å resolution, for a number of virus structures, and phase extension to a resolution sufficient to construct an atomic model. Results will also be presented that demonstrate insights obtainable for virus assembly and maturation by combining high resolution x-ray structures of one assembly form with moderate resolution cryoEM and solution x-ray data of related, transient, assembly forms.