Dynamics and rheology of polyampholyte condensates.

Abstract

Intrinsically disordered proteins (IDPs) are critical for the formation and stability of biomolecular condensates. Yet, their time-dependent dynamical and rheological properties that are central to various biological activities are only beginning to be understood. Given that many IDPs are rich in charged residues, in this work, we delineate how the arrangement of oppositely charged residues influences the equilibrium dynamics and rheology of condensed phases formed by polyampholytic disordered proteins. We show that the dynamics of polyampholytic sequences slow down with increasing charge segregation, and are correlated with the chain-level properties in dilute solutions. Interestingly, the observed trend in dynamics also holds when the protein concentration is fixed, albeit qualitatively, highlighting the effect of charge patterning and dilute phase properties in controlling the condensed phase dynamics. Under steady flow conditions, we show that increasing charge segregation governs the changes in rheological properties due to the changing nature of intermolecular interactions. Finally, guided by the trends in rheological properties, we show that polyampholyte conformations under flow exhibit a scaling behavior with the flow strength, highlighting that their conformational response to flow strength is independent of charge patterning. Our findings reveal the dynamics and rheology of condensates formed by polyampholytic IDPs and their relation to the properties of such IDPs under dilute conditions.