Structure and position-specific interactions of prion-like domains in transcription factor Efg1 phase separation.

Phase separated condensates have been found across the domains of life and many types of cells. To understand their varied functions, seeing the residue-by-residue details of the structure and interactions of component protein constituents is essential. A set of transcription factors that phase-separate controls cell fate of the pathogenic yeast Candida albicans. Here, we examine the structural and interaction details of a main regulator of this process, Efg1, using NMR spectroscopy and biochemical assays. We find Efg1's phase-separating domains are not entirely disordered as often assumed but in fact contain helical regions that persist upon phase separation. We also reveal the balance of contacts formed in the condensed phase and the importance of specific residues and regions in phase separation.