Institute for Physical Chemistry, Georg-August Universität, Tammannstr. 6, 37077 Göttingen, Germany.
Institute for Organic and Biomolecular Chemistry, Georg-August Universität, Tammannstr. 2, 37077 Göttingen, Germany.
Nano Lett. 2022 Feb 9;22(3):1449-1455. doi: 10.1021/acs.nanolett.1c02491. Epub 2021 Dec 2.
A mechanism for full-length synaptotagmin-1 (syt-1) to interact with anionic bilayers and to promote fusion in the presence of SNAREs is proposed. Colloidal probe force spectroscopy in conjunction with tethered particle motion monitoring showed that in the absence of Ca the binding of syt-1 to membranes depends on the presence and content of PI(4,5)P. Addition of Ca switches the interaction forces from weak to strong, eventually exceeding the cohesion of the C2A domain of syt-1 leading to partial unfolding of the protein. Fusion of single unilamellar vesicles equipped with syt-1 and synaptobrevin 2 with planar pore-spanning target membranes containing PS and PI(4,5)P shows an almost complete suppression of stalled intermediate fusion states and an accelerated fusion kinetics in the presence of Ca, which is further enhanced upon addition of ATP.
提出了一种全长突触融合蛋白-1（syt-1）与阴离子双层相互作用并在 SNARE 存在的情况下促进融合的机制。胶体探针力谱结合束缚粒子运动监测表明，在没有 Ca 的情况下，syt-1 与膜的结合取决于 PI(4,5)P 的存在和含量。添加 Ca 会将相互作用力从弱切换到强，最终超过 syt-1 的 C2A 结构域的内聚力，导致蛋白质部分展开。用 syt-1 和突触融合蛋白 2 装备的单层小泡与含有 PS 和 PI(4,5)P 的平面孔贯穿靶膜融合显示，在 Ca 的存在下，几乎完全抑制了停滞的中间融合状态，并且融合动力学得到加速，而添加 ATP 则进一步增强了这种作用。
