Lipid organization in model membranes and living cells by Jonathan Nickels
Host: Prof. Lisa Manning/ Contact: Yudaisy Salomón Sargentón, 315-443-5960
202 Physics Bldg.
Refreshments at 3:30 pm and the talk starting at 3:45pm
The structure and function of biological membranes has been studied for more than 100 years, but only recently has the existence and role of lipid organization been recognized. Lateral lipid organization, often called domains or lipid rafts, are hypothesized to act as scalable compartments in biological membranes, providing appropriate physical environments to their resident membrane proteins. This implies that lateral lipid organization is associated with a range of biological functions, such as protein co-localization, membrane trafficking, and cell signaling, to name just a few. Because of these connections, there exists an unrealized potential to unlock new understanding and therapies to a variety of diseases based on an improved grasp of the structure and biophysical basis of lipid raft formation and properties.
This potential is tempered by a number of observational difficulties for the experimental biophysicist. Their nanoscopic size, compositional similarity with the surrounding lipids, as well as the potentially perturbing effects of some molecular probes, all limit the amount of information that can be obtained about lipid rafts from common biophysical techniques. Neutron scattering techniques have proven to be a uniquely useful tool to get around these limitations. In this talk, I will discuss recent work using scattering and simulation approaches to study lipid domains in model membrane systems. These experimental observations and subsequent analysis are significant in the context of understanding what physical mechanisms underlay the formation and stability of nanoscopic lipid heterogeneities. This work lead into current efforts to probe the structure and organization of the cell membrane in a living organism, B. subtilis, by extending these scattering based approaches in combination with a number of innovative genetic and biochemical strategies. This approach has already yielded the first direct in vivo observations of bilayer hydrophobic thickness as well as evidence for the existence of lipid rafts in this organism. Together, these approaches are establishing a platform for systematic in vitro and in vivo investigations of cell membrane organization; setting the stage to both understand and access the potential of these enigmatic membrane structures.