Biology

Dr. Senthil Arumugam
University of New South Wales, Sydney, Australia

To infect cells, the shiga toxin interacts with the glycosphingolipid Gb3, followed by toxin internalization and intracellular retrograde trafficking. The current model implies that toxin molecules cluster at the plasma membrane prior to their endocytic uptake into cells. This clustering also results in an alternative clathrin independent endocytosis. The mechanisms by which this clustering occurs remain poorly defined, notably in the absence of any indication for direct interactions between toxin molecules. We find evidence based on simulation and reconstitution experiments that membrane fluctuation-induced forces, known as thermal Casimir forces, generate an effective attraction between toxin molecules. Further, We quantitatively visualized endocytic processes of Shiga toxin in gene edited SUM159 human cells using the newly developed lattice light-sheet microscopy (LLSM) based on ultrathin non-diffracting light sheets. I will describe novel methodologies to quantitatively study distinct endocytic routes and clustering at the whole cell level using automated analysis.