Extended Data Fig. 2: An emerging model for RNA phase separation coupled percolation (PSCP) behaviour.
From: RNAs undergo phase transitions with lower critical solution temperatures
(a) The observed hierarchy of LCST-type phase transition propensity of RNA bases and the phosphate backbone. (b) An enthalpic model of RNA phase separation. Here, RNA in an ensemble of minimum free energy structures (left) is heated, thereby denaturing the RNA. Subsequent cooling below Tph should enable the RNA to undergo a UCST transition. This model implies that enthalpic interactions such as hydrogen bonding and base-stacking drive RNA phase separation. (c) PSCP model of RNA condensation. In this model desolvation entropy drives the self-association of RNA to form phase-separated condensates upon heating. During subsequent cooling, the rank order of the phase separation temperature (LCPT or Tph) and the percolation temperature (Tprc) determines refolding vs. condensate arrest. When Tph>Tprc, the system undergoes reversible phase separation whereas in cases of Tph< Tprc, the system shows hysteretic phase behaviour. Our experimental and computational results clearly show that RNA condensation proceeds via this pathway.
