eTOC Blurb: The RNA helicase eIF4A limits stress granule formation by reducing RNA condensation.
Highlights:•! RNA condensates promote intermolecular RNA-RNA interactions at their surfaces! •! eIF4A helicase activity limits the recruitment of RNAs to stress granules in cells! •! eIF4A helicase activity reduces the nucleation of stress granules in cells! •! Recombinant eIF4A1 inhibits the condensation of RNA in vitro in an ATP-dependent manner! Keywords: DEAD-box protein, RNA-RNA interactions, stress granule, ribonucleoprotein ! 2
SUMMARY:Stress granules are condensates of non-translating mRNAs and proteins involved in the stress response and neurodegenerative diseases. Stress granules are proposed to form in part through intermolecular RNA-RNA interactions, although the process of RNA condensation is not well understood. In vitro, we demonstrate that the minimization of surface free energy promotes the recruitment and interaction of RNAs on RNA or RNP condensate surfaces. We demonstrate that the ATPase activity of the DEAD-box RNA helicase eIF4A reduces RNA recruitment to RNA condensates in vitro and in cells, as well as limiting stress granule formation. This defines a new function for eIF4A, and potentially other RNA helicases, to limit thermodynamically favored intermolecular RNA-RNA interactions in cells, thereby allowing for proper RNP function.