course: SNARE machinery is optimized for ultra-fast fusion
speaker: Matthieu Caruel (Université Paris-Est Créteil)abstract: Neurotransmitter release from synaptic vesicles is a fundamental biological phenomenon enabling the communication between neurons. This process requires the vesicle to fuse with the neuron membrane in less than 1ms, which is exceptionally fast considering that a spontaneous thermally driven fusion would require seconds. We argue that the SNARE complexes, enabling this process, act collectively as a muscle-type machinery whose swift contraction brings the vesicle close enough to the membrane so that the remaining barrier can be overcome by thermal fluctuations. While the molecular origin of a single SNARE zipping has been lately the subject of intense research, comparatively little attention was paid to the mechanical coupling between individual SNAREpins in situ. By drawing on an analogy with the collective power-stroke in muscles, we reveal the crucial role of elastic interactions within a team of N SNAREpins. We show that such interactions can produce collective zipping at sub-millisecond timescales if the team size is optimal with N=4-6. We provide a prototypical description of such cooperative fusion as a two stage reaction where the transition rates are controlled by the mechanical feedback. The proposed model will prove useful for the description of a large variety of biophysical phenomena involving ultra fast protein-mediated folding processes.
timetable:
Tue 9 Oct, 12:00 - 13:00, Aula Dini
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