Date(s) - 02/03/2016
3:30 pm - 4:30 pm
Title: Membranes: The lipid â??cross-talkâ?
Speaker: Dr. Ursula Perez-Salas
Institute: University of Illinois
Location: ABB 102
Lipids are amphiphilic molecules that love and hate water simultaneously and self-assemble into a lipid bilayer that is a universal structure of all cell membranes. The membraneâ??s hydrophobic interior is a 3nm-thick film that separates the interior of the cells from the surrounding environment. Structures inside the cell, such as the nucleus, evolved to be bounded by membranes in eukaryote cells; in fact, it is the hallmark that sets them apart from prokaryotic cells. Hence, biological membranes are not only life/death boundaries for cells but are also necessary for the existence of higher organisms like us. However, the mere function of â??confining barrierâ? does not explain why eukaryotic cells invest substantial resources in generating thousands of different lipids (~5% of their genes!) to form membranes. Indeed, the lipid composition of individual membranes within a cell varies significantly. Consider the case of cholesterol: the endoplasmic reticulum, where it is synthesized, contains barely 1% of the total cell cholesterol, while the plasma membrane contains about 40%. So the question arises: how do cells create these unique compositions and multiple functionalities in their individual membranes? The answer to this question is explained in part by thermally-driven properties of lipid membranes. In this talk I will present results from our ongoing efforts to map the energy landscape of lipid motion between distinct membranes and within a single membrane, as well as discuss lipid organization within complex (multi-lipid) membranes and provide evidence for biological consequences. These recent efforts concentrate primarily on neutron scattering techniques that, I will argue, are highly desirable because other probing techniques potentially can be too invasive, resulting in skewed results.