University of Minnesota
School of Physics & Astronomy

Physics and Astronomy Calendar

Thursday, November 7th 2019
10:10 am:
Biophysics Seminar in 120 PAN
Speaker: Comert Kural, Ohio State University
Subject: Curvature Generation by Endocytic Clathrin Coats: Super-resolution Imaging Resolves Forty Years of Controversy

Clathrin-mediated endocytosis is the most extensively studied internalization mechanism of membrane lipids and proteins from the cell surface. Over the past decades, a multitude of biophysical and biochemical methodologies have been employed to elucidate structural and dynamic properties of endocytic clathrin coats. However, fundamental aspects of clathrin-mediated endocytosis remain controversial due to the lack of experimental approaches that allow correlation of ultra-structural and dynamic properties of clathrin-coated structures. Using electron micrographs, it was originally proposed that clathrin initially grows into a flat array (i.e., clathrin plaques) on the plasma membrane prior to transitioning into a curved coat. Flat-to-curved transition of clathrin coats during endocytic vesicle formation was rejected by others as it requires a substantial structural rearrangement, which is energetically unfavorable. As an alternative, it was suggested that curved clathrin-coated structures form gradually without a major structural rearrangement. In this study, we used structured illumination microscopy in the total internal reflection mode to monitor curvature formation by clathrin coats during assembly of individual endocytic complexes within cultured cells and tissues of developing metazoan organisms. Our analyses very clearly demonstrate that endocytic clathrin coats acquire curvature without a major flat-to-curved transition that requires an extensive reorganization of the clathrin lattice. Altogether, our results signify the importance of employing methodologies comprising high resolution in both spatial and temporal dimensions for constructing dynamic models.

Faculty Host: Jochen Mueller

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