Activity-dependent interactions of NSF and SNAP at living synapses.

As core components of the neurotransmitter release apparatus, SNAREs, NSF and SNAPs mediate fusion of neurotransmitter-filled synaptic vesicles within specialized regions of the presynaptic plasma membrane known as active zones (AZs). The present study combines genetic approaches in Drosophila with biochemical and live-imaging methods to provide new insights into the in vivo behavior and interactions of NSF and SNAP in neurotransmitter release. This work employs a temperature-sensitive (TS) paralytic NSF mutant, comatose, to show that disruption of NSF function results in activity-dependent redistribution of NSF and SNAP to periactive zone (PAZ) regions of the presynaptic plasma membrane and accumulation of protein complexes containing SNAREs, NSF and SNAP. Fluorescence Resonance Energy Transfer (FRET) and Fluorescence Recovery After Photobleaching (FRAP) studies in comatose revealed that NSF and SNAP exhibit activity-dependent binding to each other within living presynaptic terminals as well as distinctive interactions and mobilities. These observations extend current models describing the spatial organization of NSF, SNAP and SNARE proteins in synaptic vesicle trafficking.