Electrostatic interactions and structural transformations in viral shells

Area of Science:

• Structural biology
• Biophysics
• Computational modeling

Background:

• Viral capsids are protein shells protecting genetic material.
• Environmental factors like pH can induce structural changes in viral capsids.
• Electrostatic interactions between proteins play a crucial role in capsid assembly and stability.

Purpose of the Study:

• To model the impact of electrostatic interactions on viral capsid structure and dynamics.
• To explain capsid faceting and subunit deformation using a biophysical model.
• To investigate the role of electrostatic and elastic forces in coronavirus shell morphology.

Main Methods:

• Development of a 2D elastic shell model with embedded point charges representing proteins.
• Analysis of electrostatic interactions and their influence on capsid geometry.
• Comparative study using examples of bacteriophage P22, Nudarelia capensis omega virus (NωV), and coronaviruses.

Main Results:

• Modification of electrostatic interactions alters capsid size, shape, and induces hexamer deformations.
• The model explains the transition of hexamers from skewed to regular shapes during capsid faceting.
• Electrostatic and elastic effects successfully account for the distribution of spikes on coronavirus shells.

Conclusions:

• Electrostatic interactions are a key determinant of viral capsid structure and conformational changes.
• The proposed model provides a mechanistic explanation for capsid morphology and subunit organization.
• The findings offer insights into viral assembly, stability, and potential therapeutic targets.