Protein Design is a Key Factor for Subunit-subunit Association

TL;DR

This study uses a simplified statistical mechanics model to explore how protein subunit interactions and design influence the stability and association behavior of dimers, revealing key features of quaternary structure formation.

Contribution

It demonstrates that protein design procedures naturally favor amino acids with stronger mutual interactions, affecting dimer stability and hysteresis behavior.

Findings

Force curves show jumps and hysteresis loops during association/dissociation.

Design improves dimer stabilization and increases hysteresis loop width.

The model captures key features of monomer interactions observed experimentally.

Abstract

Fundamental questions about the role of the quaternary structures are addressed using a statistical mechanics off-lattice model of a dimer protein. The model, in spite of its simplicity, captures key features of the monomer-monomer interactions revealed by atomic force experiments. Force curves during association and dissociation are characterized by sudden jumps followed by smooth behavior and form hysteresis loops. Furthermore, the process is reversible in a finite range of temperature stabilizing the dimer. It is shown that in the interface between the two monomeric subunits the design procedure naturally favors those amino acids whose mutual interaction is stronger. Furthermore it is shown that the width of the hysteresis loop increases as the design procedure improves, i.e. stabilizes more the dimer.