Architecture of small RNA viruses

Abstract

Symmetric organization of biological macromolecules is necessary for certain structural and functional requirements of living cells. The mechanisms by which biomolecules assemble unambiguously into unique structures has been a central theme of investigation in molecular biology. Simple viruses consist of a nucleic acid core which codes for the genetic information surrounded and protected by a protein coat or capsid. In a large majority of the cases, the protein coats possess exact icosahedral symmetry. Developments in experimental X-ray crystallography and computer technology has led recently to the elucidation of the architecture of several viruses. Systematic studies on the structure of the protein subunits, their location and orientation on the icosahedral capsid, and the details of interaction between subunits has provided some insights into the mechanisms of error free virus assembly. However, the structures of even the simplest viruses are sufficiently complex and do not lead to complete understanding of the pathway of assembly by an examination of the final structure. The current state of research in this fast advancing area is briefly reviewed.