Impact of reactive environment on phase separation of proteins and RNAs in a minimalist model of nucleoplasm

The phase separation concept has recently emerged as the principal mechanism driving the formation of biomolecular condensates. These condensates are membraneless organelles assembled from a mixture of proteins and RNAs components such as ribonucleoprotein granules and other nuclear bodies. The transience and environmental sensitivity of biomolecular condensation are strongly suggestive of kinetic gene-regulatory control of phase separation. To better understand how kinetic aspects controlling biomolecular phase-separation, we have constructed a minimalist model of the reactive nucleoplasm to study liquid-liquid phase separation in ternary protein-RNA-nucleoplasm coupled to non-equilibrium and spatially dependent gene expression. We find a broad range of kinetic regimes through an extensive set of simulations where the interplay of phase separation and reactive timescales can generate heterogeneous multi-modal gene expression patterns. Furthermore, the significance of this finding is that heterogeneity of gene expression is linked directly with the heterogeneity of length scales in phase-separated condensates.