Markus Deserno from Carnegie Mellon University is supported by the Chemical Theory, Models and Computational Methods Program in the Division of Chemistry to develop predictive theoretical and computational models for lipid membranes at very small scales. The Condensed Matter and Materials Theory Program in the Division of Materials Research also contributes to this award. Lipid membranes are a major structural components of all living cells. They separate a cell from its environment and often divide cells into smaller specialized compartments, called "organelles". In dividing cells, membranes assume a great variety of intricately shapes. While researchers have excellent theoretical and computational models to describe some shapes, others are less well understood, even though these shapes may have key roles in cellular processes. Professor Deserno and his research group are developing better theories for understanding the shapes of lipid membranes and how this affects the cell function. Furthermore, this project advances learning, by providing many examples for classroom and homework material in both undergraduate and graduate courses (statistical thermodynamics, biological physics), as well as pedagogically-instructive scripts for theoretical or computational modeling tutorials. The topic offers opportunities for productive undergraduate research projects. Special efforts are made to attract minority students to science using outreach projects with both middle and high schools in Pittsburgh. Demonstration materials are made of everyday materials such as paper and plastic foils. The ability to manipulate such materials quantitatively guide students from intuitively-familiar ideas about mechanical stability, as applied to buildings and bridges, to their unexpected applications in cell biology?related to understanding the human body.
This award supports theoretical and computational research and education to improve the quantitative description of lipid membrane elasticity at the nanoscale. The project seeks to extend the classical coupling between membrane curvature and lipid tilt to biquadratic order, opening the door to understanding numerous new cell biology phenomena. The research group confronts the refined theory with a broad repertoire of computational and experimental data, to thoroughly test the theory and extract underlying elastic parameters needed for further predictions. The researchers extend the theoretical framework to encompass the challenging but biologically common situation of membranes that not only consists of a mixture of lipids, but whose composition might differ between the two membrane leaflets (asymmetric membranes). Finally, the team predicts emergent membrane properties such as edge tensions or fission barriers, or more generally, situations involving highly curved regions that push present elastic membrane theories beyond their limits. As an especially important application, the process of membrane fission is being studied through a combination of theoretical and coarse-grained computational modeling. This work is elucidating the stresses between the lipid membrane and the enclosing dynamin filament, the importance of symmetry-breaking end-effects, and the role of thermal fluctuations; and the consequence of active constriction.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
