Disordered protein conformation upon crowding and phase separation

PGL-3 (693 a.a., ~75 kDa) is a C. elegans germ granule scaffold protein that phase separates into membrane-less condensates in vivo and in vitro. Liquid-liquid phase separation depends on temperature and salt concentration, and results in dense and dilute co-existing phases with over 100-fold difference in protein concentration. This vast concentration disparity between the dense and dilute regimes poses the question: what are the protein's conformational states as the concentration increases from dilute towards dense? PGL-3 has two globular domains followed by an intrinsically disordered tail. While one of the folded domains participates in dimerization, the role of the other one and the disordered tail is unclear. We aim to obtain structural information in dilute, concentrated below phase separation, and phase separated conditions to establish the effect of salt, protein concentration and temperature on structure.