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Mardi 24 mars 2015-14:00

From complex biological membranes to protein self-assembly

Anne-Florence Bitbol (Lewis-Sigler Institute for Integrative Genomics and Department of Physics, Princeton University)

par Gabriel LeMarié - 24 mars 2015

Biological membranes are essentially lipid bilayers, but they contain various inclusions, in particular membrane proteins. In addition, they are surrounded by a heterogeneous and constantly changing environment. In the first part of my seminar, I will discuss some of the generic physical effects of the presence of inclusions, or of environmental changes, on a lipid bilayer. I will first focus on the Casimir-like interaction between two membrane inclusions, going beyond the thermal equilibrium value of this membrane-mediated interaction. Then, I will present a theoretical description of the dynamics of a membrane submitted to a local chemical perturbation of its environment, and a comparison to experimental results.

Self-assembled multi-protein complexes play key roles in cells, e.g., as molecular motors, enzymes, channels, and receptors. In the second part of my seminar, I will discuss some aspects of the link between functions and constraints in multi-protein complexes. Functional interactions between proteins forming these complexes impose constraints on their evolution, on their abundances, etc. In turn, the features of self-assembly can be harnessed into function. I will focus on the regulation of the enzyme CTP synthetase by polymerization, and on the constraints on the abundances of chemotaxis proteins due to the requirements of fast signaling.

Post-scriptum :

contact : M. Manghi