Dynamic arrest and aging of biomolecular condensates are modulated by low-complexity domains, RNA and biochemical activity

Biomolecular condensates require suitable control of material properties for their function. Here we apply Differential Dynamic Microscopy (DDM) to probe the material properties of an in vitro model of processing bodies consisting of out-of-equilibrium condensates formed by the DEAD-box ATPase Dhh1 in the presence of ATP and RNA. By applying this single-droplet technique we show that condensates within the same population exhibit a distribution of material properties, which are regulated on several levels. Removal of the low-complexity domains (LCDs) of the protein decreases the fluidity of the condensates. Structured RNA leads to a larger fraction of dynamically arrested condensates with respect to unstructured polyuridylic acid (polyU). Promotion of the enzymatic ATPase activity of Dhh1 reduces aging of the condensates and the formation of arrested structures, indicating that biochemical activity and material turnover can maintain fluid-like properties over time. Here the authors analyze material properties and aging of active phase-separated condensates by Differential Dynamic Microscopy. Arrested states are promoted by structured RNA. Low-complexity domains and biochemical reaction keep the droplets fluid-like.

Automated summary

In this study, the material properties and aging of biomolecular condensates were analyzed using Differential Dynamic Microscopy (DDM). The results showed that the fluidity of the condensates is regulated by protein domains and structured RNA. Biochemical reactions can maintain the fluid-like properties of the condensates.