Jamie Shiah L&S Sciences
Investigating the membrane remodeling activity of ESCRT-III helical polymers with ATPase spastin
The endosomal sorting complex required for transport (ESCRT) complexes encompass an evolutionarily conserved, multi-subunit machinery that mediates unique membrane remodeling and scission away from the cytoplasm. This requires stabilization of negative membrane curvature, as induced by the ESCRT complexes.
Now, studies have shown that ESCRTs can also direct membrane budding of the opposite topology, akin to that of clathrin-mediated endocytosis by dynamin. Human ESCRT-III subunits, charged multivesicular body protein (CHMP1B) and increased sodium tolerance 1 (IST1), co-polymerize to form spirals coating the outside of membrane tubules to facilitate positive membrane curvature in vitro and in vivo. On another note, CHMP1B recruits AAA ATPase spastin to endosomes and the cytokinetic midbody, mediating microtubule severing and scission in cytokinesis. My project aims to reproduce the assembly of these ESCRT-III polymers wrapped around small unilamellar vesicles (SUVs), and take the experiment one step further by adding spastin and ATP to promote scission of these microtubules through optical tweezing and membrane pulling nanotube methods. The scission of CHMP1B and IST1 coated membrane tubes by spastin would illuminate the possibility of yet another pathway through which membranes remodel in the cell.