Sticky Interactions Govern Sequence-Dependent Dynamics in Biomolecular Condensates

Abstract

Intrinsically disordered proteins (IDPs) play a central role in shaping the dynamics and material properties of biomolecular condensates. Understanding how sequence features determine these properties is critical for elucidating physiological function and guiding the rational design of synthetic condensates. Here, we use molecular dynamics simulations to investigate condensates formed by model IDPs with systematically varied chain length and charge patterning, two features characteristic of natural IDPs. Our results show that chain relaxation times, governed by sequence-dependent electrostatic interactions, quantitatively predict condensate viscosity and diffusivity. These condensates exhibit dynamics consistent with a crossover regime between Rouse and reptation behavior. While the Rouse model with idealized friction fails to capture sequence effects, the sticky Rouse model, which incorporates transient interchain contact lifetimes, accurately predicts chain reconfiguration times and, consequently, macroscopic material properties. This work establishes a predictive, sequence-resolved framework that links molecular interactions to condensate dynamics across length and time scales.