Desmosome architecture derived from molecular dynamics simulations and cryo-electron tomography

Area of Science:

• Cell biology
• Structural biology
• Biophysics

Background:

• Desmosomes are vital cell-cell junctions that maintain tissue integrity under mechanical stress.
• The precise architecture of desmosomes, particularly the arrangement of cadherins, remains poorly understood despite known cadherin structures.

Purpose of the Study:

• To elucidate the three-dimensional architecture of desmosomes.
• To understand how desmosome structure relates to their mechanical function.

Main Methods:

• Cryo-electron tomography (cryo-ET) was used to visualize individual desmosomal cadherins.
• Sub-tomogram averaging was combined with atomistic molecular dynamics (MD) simulations.
• In silico screening of potential cadherin arrangements based on biophysical properties.

Main Results:

• Cryo-ET revealed variable cadherin shapes, spacing, and tilts.
• A sub-tomogram average achieved a resolution of approximately 26 Å.
• A truss-like cadherin arrangement was identified, consistent with observed electron microscopy data.

Conclusions:

• The study proposes a novel model for desmosome architecture based on a truss-like cadherin arrangement.
• This model explains the unique biophysical properties and mechanical strength of desmosomes.
• The integration of cryo-ET and MD simulations provides a powerful approach for studying dynamic cellular assemblies.