SOADOPP · Supramolecular organization and dynamics of presynaptic proteins

Since the prophetic vision of the German scientist Emil du Bois-Reymond in 1877 that put forward the hypothesis of the chemical nature of synaptic transmission, a large number of biochemical, genetic and neuro-physiological studies have revealed all the components that are involved in synaptic vesicle (SV) exocytosis. This complex action-potential-triggered process, in which the entry of calcium ions (Ca2+) into the presynaptic compartment induces a milliseconds-fast fusion of neurotransmitter-containing SVs with the presynaptic plasma membrane (PM), requires a number of so-called presynaptic proteins playing different roles. To date, despite all the knowledge acquired about presynaptic proteins, the question how they carry out this fast process remains unanswered. Recently, it was hypothesized that the presynaptic proteins are organized in specific supramolecular arrangements and do cooperate to achieve this remarkable feat. However, the study of presynaptic protein arrangement and functioning at nanometer isotropic scale is challenging, and decades of research were unable to resolve this phenomenon. In this project, I plan to study the three-dimensional supramolecular structures of the presynaptic proteins during SV exocytosis at nanometer isotropic resolution, and its structural dynamics on the nanometer length scale with microsecond temporal resolution. For this purpose, I will combine the super-resolution technique Single-Molecule Metal-Induced Energy Transfer (smMIET), developed by the host group, with the single-molecule localization microscopy (SMLM) methods of DNA-PAINT and MINFLUX. The overall importance of this proposal in understanding the Ca2+-triggered SV fusion is that it is essential to understand how synapses and ultimately the brain work, and all derived knowledge and applications that comes with it.