From the Department of Neurobiology.
From the Department of Neurobiology, the AG Biomolecular Spectroscopy and Single-Molecule Detection, and.
J Biol Chem. 2014 Jun 6;289(23):16326-35. doi: 10.1074/jbc.M114.556803. Epub 2014 Apr 28.
Neuronal exocytosis is mediated by soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins. Before fusion, SNARE proteins form complexes bridging the membrane followed by assembly toward the C-terminal membrane anchors, thus initiating membrane fusion. After fusion, the SNARE complex is disassembled by the AAA-ATPase N-ethylmaleimide-sensitive factor that requires the cofactor α-SNAP to first bind to the assembled SNARE complex. Using chromaffin granules and liposomes we now show that α-SNAP on its own interferes with the zippering of membrane-anchored SNARE complexes midway through the zippering reaction, arresting SNAREs in a partially assembled trans-complex and preventing fusion. Intriguingly, the interference does not result in an inhibitory effect on synaptic vesicles, suggesting that membrane properties also influence the final outcome of α-SNAP interference with SNARE zippering. We suggest that binding of α-SNAP to the SNARE complex affects the ability of the SNARE complex to harness energy or transmit force to the membrane.
神经元胞吐作用由可溶性 N-乙基马来酰亚胺敏感因子附着蛋白受体（SNARE）蛋白介导。在融合之前，SNARE 蛋白形成桥接膜的复合物，然后向 C 末端膜锚定组装，从而启动膜融合。融合后，SNARE 复合物通过 AAA-ATP 酶 N-乙基马来酰亚胺敏感因子（N-ethylmaleimide-sensitive factor）解体，该因子需要辅助因子 α-SNAP 首先结合到组装的 SNARE 复合物上。使用嗜铬细胞颗粒和脂质体，我们现在表明，α-SNAP 本身会干扰膜锚定的 SNARE 复合物在拉链反应中途的拉链，将 SNARE 蛋白固定在部分组装的反式复合物中并阻止融合。有趣的是，这种干扰不会对突触小泡产生抑制作用，这表明膜特性也会影响 α-SNAP 对 SNARE 拉链的干扰的最终结果。我们认为，α-SNAP 与 SNARE 复合物的结合会影响 SNARE 复合物利用能量或向膜传递力的能力。
