Viral capsid equilibrium dynamics reveals nonuniform elastic properties

Area of Science:

• Biophysics
• Materials Science
• Structural Biology

Background:

• Continuum mechanical properties of biomolecules are governed by long wavelength, low-frequency motions.
• Traditional models of elastic shells often simplify behavior using only Young's modulus (Y) and bending modulus (κ).
• Biomolecular structures exhibit heterogeneity and anisotropy, potentially deviating from isotropic elastic shell theory.

Purpose of the Study:

• To identify the elastic moduli necessary for describing the two-dimensional elastic behavior of viral capsids.
• To investigate the functional relevance of different moduli in various deformation modes.
• To compare theoretical predictions with experimental data, particularly from atomic force microscopy.

Main Methods:

• Analysis of low-frequency vibrational modes using a spherical harmonic basis set.
• Application of the theoretical framework to the T = 3 cowpea chlorotic mottle virus capsid.
• Estimation of the nanoindentation modulus based on the derived elastic moduli.

Main Results:

• Identification of four distinct elastic moduli required for describing capsid elasticity.
• Demonstration that capsid mechanics deviates from simplified homogeneous, isotropic linear elastic shell theory.
• The derived nanoindentation modulus aligns with experimental measurements for the cowpea chlorotic mottle virus.

Conclusions:

• A more comprehensive set of elastic moduli is essential for accurately modeling biomolecular continuum mechanics.
• The developed model provides functional insights into capsid deformation relevant to experimental techniques like atomic force microscopy.
• This work advances the understanding of viral capsid mechanics and its relationship to structural properties.