The structures of turnip crinkle and tomato bushy stunt viruses: I. A small protein particle derived from turnip crinkle virus

A small protein particle can be produced by degrading turnip crinkle virus. This particle has a diameter of 200 Å compared with 330 Å for the virus particle and could either be a virus core or a reaggregation product. The small particle appears to be composed only of protein which is identical or very similar to the protein of the whole virus. No chemical evidence has been obtained for the hypothesis that the small particles are virus cores but their assembly from virus protein can easily be demonstrated

The structures of turnip crinkle and tomato bushy stunt viruses: II. The surface structure: Dimer clustering patterns

Electron microscope images of negatively-stained particles of turnip crinkle and tomato bushy stunt viruses have been analysed. In both cases the particle surface has been shown to consist of 90 morphological units located in the 2-fold positions of the T = 3 icosahedral surface lattice. Such morphological units would then be expected to arise through clustering of the structure units in dimers, making a total of 180 structure units in the protein shell. Smaller particles obtained by degrading turnip crinkle virus have been similarly shown to have 30 morphological units arranged according to the dimer clustering pattern of the T = 1 icosahedral surface lattice. The images of both viruses and of the small particles show extra density in the positions of the 5-fold axes which may either be due to the presence of a second protein component or to clustering of the subunits at an inner radius in these positions

X-ray analysis of the disk of tobacco mosaic virus protein: I. Crystallization of the protein and of a heavy-atom derivative

The crystallization of an aggregate of the protein subunit of tobacco mosaic virus is described. Large single crystals suitable for X-ray analysis have been obtained, and an isomorphous heavy-atom derivative prepared

X-ray analysis of the disk of tobacco mosaic virus protein: II. The packing arrangement in the crystal

By a combined X-ray and electron microscopic analysis, the asymmetric unit of the crystal of tobacco mosaic virus protein has been identified with the disk aggregate, of molecular weight 600,000, composed of two rings each containing 17 subunits. The packing of the disks in the crystal has been determined, and consists of an approximately body-centred array of stacks comprising two disks each