Dr. Iwan Schaap, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh
Tuesday 17th January 2017, 1.00 p.m., Stacey Lecture Theatre 1
A major route to take up molecules into cells is via Clathrin-mediated-endocytosis. Clathrin proteins self-assemble into curved lattices that interact with cellular membrane to induce their curvature. This eventually leads to the invagination of ~100 nm small Clathrin coated vesicles containing the molecules. Although Clathrin-mediated-endocytosis is a clear example of a mechanically driven biological process, remarkably little is known about the mechanics of clathrin lattices. We used atomic force microscopy and finite element analysis to investigate the nano-mechanical properties of single clathrin cages. We found that they are surprisingly soft with a stiffness of just ~0.03 N/m, an order of magnitude lower than that of viruses but comparable to the membrane vesicle that they enclose. This low stiffness, which can be modulated by regulatory proteins, suggest a delicate balance between cage and membrane mechanics rather than a rigid cage that simply imposes its curvature onto the membrane.