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Swelling and softening of the cowpea chlorotic mottle virus in response to pH shifts.

Publication ,  Journal Article
Wilts, BD; Schaap, IAT; Schmidt, CF
Published in: Biophysical journal
May 2015

Cowpea chlorotic mottle virus (CCMV) forms highly elastic icosahedral protein capsids that undergo a characteristic swelling transition when the pH is raised from 5 to 7. Here, we performed nano-indentation experiments using an atomic force microscope to track capsid swelling and measure the shells' Young's modulus at the same time. When we chelated Ca(2+) ions and raised the pH, we observed a gradual swelling of the RNA-filled capsids accompanied by a softening of the shell. Control experiments with empty wild-type virus and a salt-stable mutant revealed that the softening was not strictly coupled to the swelling of the protein shells. Our data suggest that a pH increase and Ca(2+) chelation lead primarily to a loosening of contacts within the protein shell, resulting in a softening of the capsid. This appears to render the shell metastable and make swelling possible when repulsive forces among the capsid proteins become large enough, which is known to be followed by capsid disassembly at even higher pH. Thus, softening and swelling are likely to play a role during inoculation.

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Published In

Biophysical journal

DOI

EISSN

1542-0086

ISSN

0006-3495

Publication Date

May 2015

Volume

108

Issue

10

Start / End Page

2541 / 2549

Related Subject Headings

  • Hydrogen-Ion Concentration
  • Elastic Modulus
  • Capsid
  • Calcium Chelating Agents
  • Calcium
  • Bromovirus
  • Biophysics
  • 51 Physical sciences
  • 34 Chemical sciences
  • 31 Biological sciences
 

Citation

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ICMJE
MLA
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Wilts, B. D., Schaap, I. A. T., & Schmidt, C. F. (2015). Swelling and softening of the cowpea chlorotic mottle virus in response to pH shifts. Biophysical Journal, 108(10), 2541–2549. https://doi.org/10.1016/j.bpj.2015.04.019
Wilts, Bodo D., Iwan A. T. Schaap, and Christoph F. Schmidt. “Swelling and softening of the cowpea chlorotic mottle virus in response to pH shifts.Biophysical Journal 108, no. 10 (May 2015): 2541–49. https://doi.org/10.1016/j.bpj.2015.04.019.
Wilts BD, Schaap IAT, Schmidt CF. Swelling and softening of the cowpea chlorotic mottle virus in response to pH shifts. Biophysical journal. 2015 May;108(10):2541–9.
Wilts, Bodo D., et al. “Swelling and softening of the cowpea chlorotic mottle virus in response to pH shifts.Biophysical Journal, vol. 108, no. 10, May 2015, pp. 2541–49. Epmc, doi:10.1016/j.bpj.2015.04.019.
Wilts BD, Schaap IAT, Schmidt CF. Swelling and softening of the cowpea chlorotic mottle virus in response to pH shifts. Biophysical journal. 2015 May;108(10):2541–2549.
Journal cover image

Published In

Biophysical journal

DOI

EISSN

1542-0086

ISSN

0006-3495

Publication Date

May 2015

Volume

108

Issue

10

Start / End Page

2541 / 2549

Related Subject Headings

  • Hydrogen-Ion Concentration
  • Elastic Modulus
  • Capsid
  • Calcium Chelating Agents
  • Calcium
  • Bromovirus
  • Biophysics
  • 51 Physical sciences
  • 34 Chemical sciences
  • 31 Biological sciences