1986 Volume 26 Issue 4 Pages 147-156
Studies of self-assembly of tobacco mosaic virus (TMV) are briefly reviewed and X-ray fiber diffraction analysis of TMV is described. The fiber diffraction analysis has enabled a molecular model of the intact virus to be built, based on a map at 3.6A resolution derived from five separated Bessel orders. This has been made possible by advances in the solution of the fiber diffraction phase problem. It is now possible to understand much of the chemical basis of TMV assembly, particularly in terms of inter-subunit electrostatic interactions and RNA binding. Consideration of the molecular structure in conjunction with physical chemical studies by other groups suggests that the nucleating aggregate for initiation of TMV assembly is not the 34-subunit disk, but a short (about two turns) helix of protein subunits, probably inhibited from further polymerization by the disordering of a peptide loop near the inner surface of the virus.
