26474065

PMC5221516

Compartmentalization in cells is central to the spatial and temporal control of biochemistry. In addition to membrane-bound organelles, membrane-less compartments form partitions in cells. Increasing evidence suggests that these compartments assemble through liquid-liquid phase separation. However, the spatiotemporal control of their assembly, and how they maintain distinct functional and physical identities, is poorly understood. We have previously shown an RNA-binding protein with a polyQ-expansion called Whi3 is essential for the spatial patterning of cyclin and formin transcripts in cytosol. Here, we show that specific mRNAs that are known physiological targets of Whi3 drive phase separation. mRNA can alter the viscosity of droplets, their propensity to fuse, and the exchange rates of components with bulk solution. Different mRNAs impart distinct biophysical properties of droplets, indicating mRNA can bring individuality to assemblies. Our findings suggest that mRNAs can encode not only genetic information but also the biophysical properties of phase-separated compartments.

CDC Public Access

R01-GM081506/GM/NIGMS NIH HHS/United States
DP2 GM105437/GM/NIGMS NIH HHS/United States
P30 CA023108/CA/NCI NIH HHS/United States
1DP2GM105437-01/DP/NCCDPHP CDC HHS/United States
R01 GM081506/GM/NIGMS NIH HHS/United States