The structure determination of canine parvovirus at 3.25 A resolution
Abstract
Canine Parvovirus, an autonomous replicating parvovirus, represents a remarkable example of the emergence of a totally new viral pathogen. It was first identified in 1978 and has been shown to be closely related to Feline Parvovirus and Mink Enteritis Virus. Many crystal forms of canine parvovirus have been obtained and data collected from the monoclinic crystals were used to determine the structure to 3.25 A resolution. The diffraction data were collected at the Cornell High Energy Synchrotron Source (CHESS) using the oscillation photography technique. The phases for the observed structure amplitudes were intially derived from a spherical hollow shell model of the virus and then, with the help of a heavy atom derivative, eventually extended to 3.25 A resolution. The entire process of structure determination was carried out on the CYBER 205 supercomputer. An atomic model was built into the electron density using the Evans and Sutherland PS390 computer graphics system and the FRODO program of Alwyn Jones. A series of theoretical studies of molecular replacement phase refinement and extension using model structure factors has been accomplished to establish the validity of phasing starting from a spherical model. The success of these studies provided the background knowledge for solving the canine parvovirus phases ab initio. The use of molecular replacement electron density averaging for phase determination has been further extended. The central structure of the canine parvovirus polypeptide (VP2) has the same topology, namely an eight-stranded antiparallel $\beta$-barrel, as has been found in many other icosahedral RNA and DNA viruses. There are enormous insertions on the virus surface to form loops and depressions that are important for the viral functions. A substantial volume of electron density, in a pocket on the interior surface of the capsid, was shown to correspond to 11 DNA nucleotides.
Degree
Ph.D.
Advisors
Rossmann, Purdue University.
Subject Area
Biophysics|Microbiology
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