BLM helicase protein negatively regulates stress granule formation through unwinding RNA G-quadruplex structures
Yehuda M. Danino, Lena Molitor, Tamar Rosenbaum-Cohen, Sebastian Kaiser, Yahel Cohen, Ziv Porat, Hagai Marmor-Kollet, Corine Katina, Alon Savidor, Ron Rotkopf, Eyal Ben-Isaac, Ofra Golani, Yishai Levin, David Monchaud, Ian D. Hickson, Eran Hornstein
Abstract
Bloom's syndrome (BLM) protein is a known nuclear helicase that is able to unwind DNA secondary structures such as G-quadruplexes (G4s). However, its role in the regulation of cytoplasmic processes that involve RNA G-quadruplexes (rG4s) has not been previously studied. Here, we demonstrate that BLM is recruited to stress granules (SGs), which are cytoplasmic biomolecular condensates composed of RNAs and RNA-binding proteins. BLM is enriched in SGs upon different stress conditions and in an rG4-dependent manner. Also, we show that BLM unwinds rG4s and acts as a negative regulator of SG formation. Altogether, our data expand the cellular activity of BLM and shed light on the function that helicases play in the dynamics of biomolecular condensates.