Active remodeling of RNA interactions facilitates nonequilibrium steady states of protein-RNA condensates

Biomolecular condensates are membraneless organelles which organize biochemical processes within the cell. Many biomolecular condensates contain RNA and are involved in RNA metabolism. Base-pairing interactions of RNA can contribute to the normal material and dynamic state of a particular biomolecular condensate or drive a transition of the condensate into a solid-like or aggregate-like state. RNA base-pairing interactions can be tuned and remodeled by DEAD-box helicases, a class of proteins commonly found associated with biomolecular condensates, in an energy-dependent manner. In this work, we assess the effects of active RNA remodeling by a DEAD-box helicase on condensate structure, composition, and phase behavior. Through modulating enzyme activity and changing RNA substrate identity, we tie helicase activity to RNA partitioning, time-dependent condensate morphology, and time-dependent condensate dynamics. We also show that helicase activity can be leveraged to produce secondary RNA phase transitions, suggesting that DEAD-box helicase-RNA systems may offer a new frontier in active matter research.