Nano-Science Seminar: Paul M. Bendix
Please join us at https://ucph-ku.zoom.us/meeting/63910131060 for a talk by Poul Martin Bendix.
Annexins are multifunctional proteins and are often expressed in cells experiencing enhanced surface stresses. Cells employ annexins in membrane repair by Ca2+ dependent recruitment of annexins to the site of injury. Interestingly, annexins have been found to shape membranes due to their curved molecular shape and this feature opens the question whether annexins are able to sense membrane curvatures. Here, we use optical manipulation to investigate the curvature sensing ability of annexin A2, A4 and A5 in isolated plasma membranes vesicles and show that curvature sensing is affected by the oligomerization state of the protein. These results are supported by multiscale simulations showing that ANXA4 trimers exhibit optimal sensing of certain membrane curvatures. Interestingly, membrane proteins with bent shapes are found to both sense curvature cues and undergo crystallization at high density within nanotubes, a property which could play a regulatory role in a number of cell functions and cellular disorders. Finally, the function of annexins in membrane repair was studied using thermoplasmonics and I will discuss possible functional links between the biophysical properties of annexins and the membrane repair. With these novel experiments, we gain a new understanding of the mechanisms governing cell surface protein dynamics and properties of the surface of living cells.
Nano-Science Center seminars are monthly seminars with a scientific presentation featuring a guest or faculty from the Nano-Science Center. The seminars are targeted students from 2nd year and researchers, and the aim is to inspire and catalyse networking among researchers and students.