NSF Award
9207014
An architectural model of adenovirus has been developed by combining information from several areas: a high-resolution crystallographic structure of hexon, the major coat protein; image analysis of electron micrographs of capsid fragments; and biochemical stoichiometric determinations. The basic model for hexon packing is supported experimentally with a three- dimensional image reconstruction at 35 A resolution using unstained images from cryo-electron microscopy. This reveals that the virion has curved facets, provides the shapes of the vertex proteins, and suggests locations for several "cementing proteins". Hexon density will be calculated from the known atomic coordinates. Suitable contrast transfer functions will be derived to match crystallographic hexons to their electron microscopic counterparts. Hexon positions in the virion will be refined. Accurate difference density will be calculated by subtracting a hexon shell from the virion density to image vertex proteins and minor components in greater detail. The reconstruction will be extended to higher resolution. Difference imaging of mutant virions lacking structural components, and virions labelled with monoclonal antibodies, will identify these proteins and define virion epitopes. %%% The overall goal of this project is to explore the principles by which mammalian viruses are constructed from their constituent proteins with the focus on determining the molecular structure of adenovirus to high resolution.
