Stoichiometry controls the dynamics of liquid condensates of associative proteins

TL;DR

This study investigates how the ratio of proteins influences the internal dynamics of liquid condensates formed by associative proteins, revealing that balanced stoichiometry causes significant slowdown in molecular motion and affects material properties.

Contribution

It introduces a scaling analysis and molecular dynamics approach to understand how stoichiometry controls the dynamics of associative protein condensates.

Findings

Balanced stoichiometry leads to slower relaxation dynamics.

Slower dynamics impact diffusivity, viscosity, and mixing.

Predictions can be tested experimentally.

Abstract

Multivalent associative proteins with strong complementary interactions play a crucial role in phase separation of intracellular liquid condensates. We study the internal dynamics of such "bond-network" condensates comprised of two complementary proteins via scaling analysis and molecular dynamics. We find that when stoichiometry is balanced, relaxation slows down dramatically due to a scarcity of alternative partners following a bond break. This microscopic slow-down strongly affects the bulk diffusivity, viscosity and mixing, which provides a means to experimentally test our predictions.