Towards the molecular mechanism of membrane fission mediated by the ESCRT-III/Vps4 machinery

• Applicant: Dr. Joachim Moser von Filseck
• Subject Area: Biochemistry ; Biophysics ; Structural Biology ; Cell Biology
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 465120651

asdfTo maintain cellular homeostasis of its sub-compartments, eukaryotic cells require vesicular trafficking and protein machineries that mediate the membrane remodelling events therein. The ESCRT-III/Vps4 system remodels membranes using an evolutionarily ancient mechanism, possibly conserved in all three domains of life. Yet how they do it remains unclear. To answer the questions remaining on their molecular mechanism of function, I suggest a set of complementary experiments: I want to analyse the structural details of isolated ESCRT-III polymeric filaments, using cryo-electron microscopy, and identify the role of ESCRT-III subunit composition and stoichiometry. Next, I want to use cryo-electron tomography to compare isolated filaments with filaments bound to lipid vesicles to understand the interplay between filament and membrane composition and properties. Ultimately, I want to compare these in vitro reconstitutions with pathophysiological ESCRT-III/Vps4 activity in the context of viral egress with cellular cryo-electron tomography. Importantly, I want to answer the question whether large ESCRT-III assemblies are required for their physiological function and how they work there. The experimental evidence will then feed in theoretical descriptions and molecular dynamics simulations to validate their significance for membrane remodelling. These approaches would allow us to understand the mechanistic details of any membrane remodelling event inside cells. The immediate questions are challenging and require a broad strategy, as only the understanding of protein and lipid biochemistry and biophysics as well as structural insight, complemented by theoretical and modelling approaches, properly address them.

• DFG Programme: Independent Junior Research Groups
• International Connection: Switzerland
• Cooperation Partner: Professor Dr. Stefano Vanni