Events

Liquid-liquid phase separation in living biological membranes is usually described as occurring on sub-micron length scales. A stunning counterexample occurs in S. cerevisiae. When the yeast shift from the log stage of growth to the stationary stage, huge, micron-scale liquid domains appear in the membranes of the vacuole, an endosomal organelle. These phases are functionally important, enabling yeast survival during periods of stress. This talk will review recent results showing: (1) This miscibility transition is reversible as would be expected from equilibrium thermodynamics, even though it occurs in a living system. (2) Yeast actively regulate this phase transition to hold the membrane transition ~15C above the yeast growth temperature. (3) In cases when domains appear as stripes, there is no current theory that explains all physical observables of the system. This research was conducted in collaboration with the labs of Alex Merz (University of Washington) and Robert Ernst (Universität des Saarlandes).

Sarah L. Keller, the Duane and Barbara LaViolette Professor of Chemistry, is a biophysicist in the U.S. at the University of Washington in Seattle. She investigates self-assembly, complex fluids, and soft matter systems. Her research group’s primary focus concerns how lipid mixtures within bilayer membranes give rise to complex phase behavior. She is a Fellow of the American Physical Society and a Fellow of the Biophysical Society.