1ZA7

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

Summary for 1ZA7

• Entry DOI: 10.2210/pdb1za7/pdb
• Related: 1cwp
• Descriptor: Coat protein (2 entities in total)
• Functional Keywords: mutant virus capsid structure, icosahedral particle, stablizing mutation, stable mutant, beta hexamer, beta barrel, bromovirus, point mutation, icosahedral virus, virus
• Biological source: Cowpea chlorotic mottle virus
• Cellular location: Virion : P03601
• Total number of polymer chains: 3
• Total formula weight: 52803.06

Authors

Bothner, B.,Speir, J.A.,Qu, C.,Willits, D.A.,Young, M.J.,Johnson, J.E. (deposition date: 2005-04-05, release date: 2006-03-21, Last modification date: 2023-08-23)

Primary citation

Speir, J.A.,Bothner, B.,Qu, C.,Willits, D.A.,Young, M.J.,Johnson, J.E.
Enhanced local symmetry interactions globally stabilize a mutant virus capsid that maintains infectivity and capsid dynamics.
J.Virol., 80:3582-3591, 2006

PubMed Abstract: 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.

PubMed: 16537626
DOI: 10.1128/JVI.80.7.3582-3591.2006

Experimental method

X-RAY DIFFRACTION (2.7 Å)