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Experimental Models for Intracellular Organization Based on Phase Separation in Aqueous Polymer Solutions

Speaker: Christine Keating, Pennsylvania State University
Series: CBE Departmental Seminars
Location: Elgin Room (E-Quad A224)
Date/Time: Wednesday, October 10, 2012, 4:00 p.m. - 5:00 p.m.

The interior of living cells is both structurally and functionally organized.  Heterogeneity is maintained even in the absence of membranous boundaries such as those that surround organelles.  We are developing simple experimental models for cytoplasmic organization based on aqueous phase separation, which is a common phenomenon in crowded solutions of macromolecules.  When phases are present, solutes such as proteins or nucleic acids can be compartmentalized by partitioning into one of the phases.  The resulting control over local biomolecule concentrations can be used to localize reactions and improve overall reaction rates as compared to uncompartmentalized systems.  Aqueous two-phase systems can also be prepared inside cell-sized lipid vesicles by encapsulating both PEG and dextran polymers at several weight percent.  The resulting structures, where a lipid membrane surrounds two coexisting aqueous phases, are a primitive model of biological cells. These polymer-containing vesicles offer a very simple experimental model system for investigating the effects of biomacromolecule compartmentalization and polarity.