Equilibrium Dynamics of a Biomolecular Complex Analyzed at Single-amino Acid Resolution by Cryo-electron Microscopy

Area of Science:

• Structural Biology
• Biophysics
• Virology

Background:

• Biological function relies on conformational dynamics.
• Cryo-electron microscopy (cryo-EM) local resolution (LR) data may offer insights into equilibrium dynamics.
• Validation of LR data for dynamics studies was previously lacking.

Purpose of the Study:

• To validate the use of cryo-EM LR data for assessing biomolecular complex equilibrium dynamics.
• To apply this validated method to study mutant minute virus of mice (MVM) capsids.

Main Methods:

• Determined cryo-EM structure of MVM capsid.
• Correlated cryo-EM LR values with crystallographic B factors.
• Measured hydrogen/deuterium exchange (HDX) rates using mass spectrometry (HDX-MS).

Main Results:

• Cryo-EM LR values strongly correlated with crystallographic B factors and HDX-MS rates.
• Validated cryo-EM LR data as a reliable measure of equilibrium dynamics.
• Observed impaired equilibrium dynamics in mutant MVM capsids, linked to mechanical stiffening.

Conclusions:

• Cryo-electron microscopy (cryo-EM) provides a powerful method for simultaneously determining atomic structure and local equilibrium dynamics.
• This validated approach advances the study of biomolecular complex dynamics.
• Findings support a link between mechanical properties and dynamics in viral particles.