Structure-Derived Insights into Virus Assembly

Vijay S. Reddy, John E. Johnson

Research output: Chapter in Book/Report/Conference proceedingChapter

30 Scopus citations

Abstract

Viruses are self-assembling macromolecular complexes made up of nucleoprotein components; in the case of enveloped viruses, the nucleoprotein complexes are surrounded by lipid bilayers. The genetic efficiency seen in viruses is manifested in their self-assembling nature, as multiple copies of a few proteins, making repeated equivalent interactions, assemble into symmetric closed shells encapsidating their own genome (Crick and Watson, 1956). The structural work that followed the observations by Crick and Watson revealed that spherical capsids indeed display icosahedral symmetry (Finch and Klug, 1959; Klug and Finch, 1960). Because the majority of viral capsids contain more than 60 subunits, Caspar and Klug, in their seminal work, proposed a method to organize a larger number of coat protein subunits into closed shells and characterized these capsids by the triangulation (T) number (Caspar and Klug, 1962). The assembly of simple nonenveloped viruses occurs rapidly and spontaneously with a high degree of fidelity. The latter implies that the "instructions" to form closed shells (capsids) are built into their components, mainly the coat protein subunits (Caspar, 1965). If this is true, then it should be possible to gain insights into virus assembly on the basis of the structure and organization of the protein subunits in those types of capsids, which do not require any auxiliary or scaffolding proteins for the assembly. Many nonenveloped isometric viruses form a homogeneous population of virions, and hence are amenable to crystallization and subsequent high-resolution structural studies by X-ray crystallography. Since the first report of the virus structure of tomato bushy stunt virus at high resolution (Harrison et al., 1978), a significant number (74) of distinct virus/capsid structures representing 21 different families have been determined (Table I). A Web site and a database [Virus Particle Explorer (VIPER), http://mmtsb.scripps.edu/viper/] were created as a repository for all high-resolution capsid structures and their structural analyses (Reddy et al., 2001). The major driving force for such a database is to have all the virus/capsid structures oriented in one standard icosahedral convention that facilitates the subsequent rapid analysis of these structures. These structures have been analyzed in terms of protein-protein interactions, quasi-equivalence, and self-assembly pathways (Damodaran et al., 2002; Reddy et al., 1998). In this article we focus on the architecture and self-assembly of simple nonenveloped viruses whose structures have been determined at near atomic resolution.

Original languageEnglish (US)
Title of host publicationVirus Structure and Assembly
EditorsPolly Roy
Pages45-68
Number of pages24
DOIs
StatePublished - 2005
Externally publishedYes

Publication series

NameAdvances in Virus Research
Volume64
ISSN (Print)0065-3527

Bibliographical note

Funding Information:
The authors thank Professor Anette Schneemann for valuable suggestions and for critical reading of the manuscript. This work was supported by the NIH research resource: Multiscale Modeling Tools for Structural Biology (MMTSB, RR12255).

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