Poster abstracts

Poster number 3 submitted by Ibraheem Alshareedah

Liquid-Liquid Phase Transition of Protein-RNA Complexes: Droplets, Micelles and Vesicles

Ibraheem Alshareedah (Department of Physics, University at Buffalo), Priya R. Banerjee (Department of Physics, University at Buffalo)

Abstract:
Liquid-liquid phase separation of multivalent disordered proteins with RNA is prevalent in natural and biomimetic systems. Recently, we showed that protein-RNA condensation is reentrant and sensitively depends on the RNA-to-protein mixing ratio as well as the sequence-encoded protein-protein and protein-RNA interactions1. In this work, by quantitatively mapping the phase behavior of protein-RNA complexes at various mixture compositions, we report the formation of hollow vesicle-like protein-RNA condensates that are distinct from liquid droplets. These hollow condensates are preceded by micellar condensates and are formed at disproportionate mixture compositions of non-amphipathic oppositely charged proteins and RNAs2. We further show that these hollow condensates display a striking resemblance to classical vesicles formed by amphipathic biopolymers. Specifically, protein-RNA hollow condensates display fluid-like properties, liquid-crystalline order, size-dependent permeability and selective encapsulation of biomolecules. In contrast to lipid vesicles, protein-RNA hollow condensates form robustly and spontaneously upon mixing and are highly responsive to biochemical stimuli. Our findings reveal hollow vesicle-like enclosures as a new phase in the topological spectrum of protein-RNA phase separation.

References:
1 Alshareedah, I. et al. Interplay between Short-Range Attraction and Long-Range Repulsion Controls Reentrant Liquid Condensation of Ribonucleoprotein–RNA Complexes. Journal of the American Chemical Society 141, 14593-14602, doi:10.1021/jacs.9b03689 (2019).
2 Alshareedah, I., Moosa, M. M., Raju, M., Potoyan, D. A. & Banerjee, P. R. Phase transition of RNA−protein complexes into ordered hollow condensates. Proceedings of the National Academy of Sciences 117, 15650-15658, doi:10.1073/pnas.1922365117 (2020).

Keywords: Liquid-Liquid phase separation, RNA vesicles, RNA micelles