1za7

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spinqualitylabelsall models 1za7, resolution 2.70Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

The crystal structure of salt stable cowpea cholorotic mottle virus at 2.7 angstroms resolution.

Overview

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.

About this Structure

1ZA7 is a Single protein structure of sequence from Cowpea chlorotic mottle virus. Full crystallographic information is available from OCA.

Reference

Enhanced local symmetry interactions globally stabilize a mutant virus capsid that maintains infectivity and capsid dynamics., Speir JA, Bothner B, Qu C, Willits DA, Young MJ, Johnson JE, J Virol. 2006 Apr;80(7):3582-91. PMID:16537626

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