1ZA7 image
Entry Detail
PDB ID:
1ZA7
Keywords:
Title:
The crystal structure of salt stable cowpea cholorotic mottle virus at 2.7 angstroms resolution.
Biological Source:
Host Organism:
PDB Version:
Deposition Date:
2005-04-05
Release Date:
2006-03-21
Method Details:
Experimental Method:
Resolution:
2.70 Å
R-Value Work:
0.24
R-Value Observed:
0.24
Space Group:
P 21 21 21
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Coat protein
Mutations:K42R
Chain IDs:A, B, C
Chain Length:165
Number of Molecules:3
Biological Source:Cowpea chlorotic mottle virus
Primary Citation
Enhanced local symmetry interactions globally stabilize a mutant virus capsid that maintains infectivity and capsid dynamics.
J.Virol. 80 3582 3591 (2006)
PMID: 16537626 DOI: 10.1128/JVI.80.7.3582-3591.2006

Abstact

Structural transitions in viral capsids play a critical role in the virus life cycle, including assembly, disassembly, and release of the packaged nucleic acid. Cowpea chlorotic mottle virus (CCMV) undergoes a well-studied reversible structural expansion in vitro in which the capsid expands by 10%. The swollen form of the particle can be completely disassembled by increasing the salt concentration to 1 M. Remarkably, a single-residue mutant of the CCMV N-terminal arm, K42R, is not susceptible to dissociation in high salt (salt-stable CCMV [SS-CCMV]) and retains 70% of wild-type infectivity. We present the combined structural and biophysical basis for the chemical stability and viability of the SS-CCMV particles. A 2.7-A resolution crystal structure of the SS-CCMV capsid shows an addition of 660 new intersubunit interactions per particle at the center of the 20 hexameric capsomeres, which are a direct result of the K42R mutation. Protease-based mapping experiments of intact particles demonstrate that both the swollen and closed forms of the wild-type and SS-CCMV particles have highly dynamic N-terminal regions, yet the SS-CCMV particles are more resistant to degradation. Thus, the increase in SS-CCMV particle stability is a result of concentrated tethering of subunits at a local symmetry interface (i.e., quasi-sixfold axes) that does not interfere with the function of other key symmetry interfaces (i.e., fivefold, twofold, quasi-threefold axes). The result is a particle that is still dynamic but insensitive to high salt due to a new series of bonds that are resistant to high ionic strength and preserve the overall particle structure.

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