W0127

Structural Studies of Flexible Filamentous Plant Viruses by Fiber Diffraction and Crystallography. Gerald Stubbs, Christopher Bunick, Amy Kendall, and Lauren Parker, Center for Structural Biology, Vanderbilt Univ., Nashville, TN 37232, USA.

Potexviruses and potyviruses are flexible filamentous plant viruses, of great importance in basic virology, agriculture, and biotechnology. Like most flexible filaments, they do not crystallize, but we have been able to obtain good fiber diffraction patterns from oriented sols of potexviruses, and to crystallize the coat proteins of potato virus X (PVX) and papaya mosaic virus (PMV). Studies have been extended to narcissus mosaic virus, and to several potyviruses including wheat streak mosaic virus (WSMV).

Oriented sols are prepared by centrifugation and exposure to strong magnetic fields. This procedure has produced excellent potexvirus specimens. Diffraction data collected at the BioCAT beamline at APS, Argonne, have enabled us to determine the symmetry of PVX, to demonstrate the presence of deep intersecting grooves in the viral surface, and to determine the inner and outer radii of the virion and a probable location of the genomic RNA. Solution scattering from WSMV sols has allowed us to determine a probable symmetry for this virus.

Detailed structure determination of the intact viruses will probably require both the fiber diffraction data and high-resolution crystallographic structure determination of isolated coat proteins. We have obtained diffraction data from crystals of the PVX coat protein and a proteolytically cleaved form of the PMV coat protein.

Supported by grant MCB-0235653 from the NSF, and by Vanderbilt University. Use of the Advanced Photon Source was supported by the U.S. Department of Energy, Basic Energy Sciences, Office of Science, under contract No. W-31-109-ENG-38. BioCAT is a National Institutes of Health-supported Research Center RR-08630.