RNAs undergo phase transitions with lower critical solution temperatures [article]

Gable M Wadsworth, Walter J Zahurancik, Xiangze Zeng, Paul Pullara, Lien B Lai, Vaishnavi Sidharthan, Rohit V Pappu, Venkat Gopalan, Priya R Banerjee
2022 bioRxiv   pre-print
Co-phase separation of RNAs and RNA-binding proteins is thought to drive the biogenesis of ribonucleoprotein granules. RNAs can also undergo phase transitions in the absence of proteins. However, the physicochemical driving forces of protein-free RNA-driven phase transitions remain unclear. Here, we report that RNAs of various types undergo phase transitions with system-specific lower critical solution temperatures. This entropically-driven phase behavior requires Mg2+ions and is an intrinsic
more » ... ature of the phosphate backbone that is modulated by RNA bases. RNA-only condensates can additionally undergo a temperature-dependent percolation transition, which is enabled by a combination of Mg2+-dependent bridging interactions among phosphate groups and RNA base-stacking / base-pairing. Phase separation coupled to percolation can cause dynamical arrest of RNAs within condensates. The dynamical arrest of condensates formed by the RNase P ribozyme suppresses its catalytic activity. Our work highlights the need to incorporate RNA-driven phase transitions into models for RNP granule biogenesis.
doi:10.1101/2022.10.17.512593 fatcat:tcdbhcuyojd3fd3tnsratahqhu