V-ATPase Membrane Sector Associates with Synaptobrevin to Modulate Neurotransmitter Release

Abstract

Acidification of synaptic vesicles by the vacuolar proton ATPase is essential for loading with neurotransmitter. Debated findings have suggested that V-ATPase membrane domain (V0) also contributes to Ca(2+)-dependent transmitter release via a direct role in vesicle membrane fusion, but the underlying mechanisms remain obscure. We now report a direct interaction between V0 c-subunit and the v-SNARE synaptobrevin, constituting a molecular link between the V-ATPase and SNARE-mediated fusion. Interaction domains were mapped to the membrane-proximal domain of VAMP2 and the cytosolic 3.4 loop of c-subunit. Acute perturbation of this interaction with c-subunit 3.4 loop peptides did not affect synaptic vesicle proton pump activity, but induced a substantial decrease in neurotransmitter release probability, inhibiting glutamatergic as well as cholinergic transmission in cortical slices and cultured sympathetic neurons, respectively. Thus, V-ATPase may ensure two independent functions: proton transport by a fully assembled V-ATPase and a role in SNARE-dependent exocytosis by the V0 sector.

Vacuolar ATPase in Phagosome-Lysosome Fusion

“…The role of the v-ATPase complex and specifically the membrane-bound V 0 sector as a fusion-enhancing factor has been a matter of extensive investigations (13,38). With respect to the phagocytic pathway, this role has only been studied by looking at apoptotic body removal in zebrafish brain (16) where the a1-subunit of v-ATPase, despite an unaltered lysosome pH, was FIGURE 6.…”

Compensatory branching morphogenesis of stalk cells in the Drosophila trachea

“…Mutation of okg or cnj should compromise V1 and vATPase assembly, but not V0 function (Doherty and Kane, 1993;Tomashek et al, 1997). Since free V0 can bind SNAREs to promote membrane fusion (Bayer et al, 2003;Di Giovanni et al, 2010;Hiesinger et al, 2005;Liegeois, 2006;Strasser et al, 2011), it was important to test whether tracheal defects resulted from loss of vATPase function or gain of V0 membrane fusion activity. Terminal cells depleted for either V0d or c″ ( Fig.…”

V-ATPase V1 Sector Is Required for Corpse Clearance and Neurotransmission in Caenorhabditis elegans

“…This is clearly the case for different subunit a V o isoforms in yeast; proton coupling to ATPase hydrolysis is weaker in the Golgi-specific isoform than in the vacuole-specific isoform (Kawasaki- Nishi et al 2001a,b). Also, as discussed above, synaptic vesicle V o subunit a1 isoform may have a fusogenic role distinct from its function in pumping protons (Morel et al 2003;Hiesinger et al 2005;Di Giovanni et al 2010). Do V 1 subunit isoforms similarly tune V-ATPases or confer additional functions?…”

“…The V-ATPase is composed of two substructures: a catalytic domain of eight different subunits called the V 1 sector and a membrane-anchored set of subunits called the V o sector ( Figure 1A). Both sectors are required for acidification of cellular organelles; however, genetic analysis suggests that the V o domain may have an additional role in promoting membrane fusion (Peters et al 2001;Hiesinger et al 2005;Liégeois et al 2006;Sun-Wada et al 2006;Peri and Nüsslein-Volhard 2008;Di Giovanni et al 2010;Williamson et al 2010;Strasser et al 2011). To distinguish the roles of acidification and potential additional roles of the V-ATPase, it is particularly important to identify the functions of the catalytic V 1 sector.…”