Dehydration entropy drives liquid-liquid phase separation by molecular crowding.zip

Complex
coacervation driven liquid-liquid phase separation (LLPS) of biopolymers has been attracting attention as a novel
phase in living cells. Studies of LLPS in this context are typically of proteins
harboring chemical and structural complexity, leaving unclear what property is fundamental
to complex coacervation versus protein-specific. This study focus on the role
of polyethylene glycol (PEG)—a widely used molecular crowder—in LLPS. Significantly,
entropy-driven LLPS was recapitulated with charged polymers lacking
hydrophobicity and sequence complexity, and its propensity dramatically
enhanced by PEG. Experimental and field-theoretic simulation results are
consistent with PEG driving LLPS by dehydration of polymers, and show that PEG
exerts its effect without partitioning into the dense coacervate phase. It is
then up to biology to impose additional variations of functional significance
to the LLPS of biological systems.