Department of Microbiology and Molecular Genetics, Harvard Medical School and Division of Neuroscience, New England Primate Research Center, Southborough, Massachusetts, United States of America.
PLoS Pathog. 2011 Mar;7(3):e1002008. doi: 10.1371/journal.ppat.1002008. Epub 2011 Mar 31.
Botulinum neurotoxins (BoNTs) include seven bacterial toxins (BoNT/A-G) that target presynaptic terminals and act as proteases cleaving proteins required for synaptic vesicle exocytosis. Here we identified synaptic vesicle protein SV2 as the protein receptor for BoNT/D. BoNT/D enters cultured hippocampal neurons via synaptic vesicle recycling and can bind SV2 in brain detergent extracts. BoNT/D failed to bind and enter neurons lacking SV2, which can be rescued by expressing one of the three SV2 isoforms (SV2A/B/C). Localization of SV2 on plasma membranes mediated BoNT/D binding in both neurons and HEK293 cells. Furthermore, chimeric receptors containing the binding sites for BoNT/A and E, two other BoNTs that use SV2 as receptors, failed to mediate the entry of BoNT/D suggesting that BoNT/D binds SV2 via a mechanism distinct from BoNT/A and E. Finally, we demonstrated that gangliosides are essential for the binding and entry of BoNT/D into neurons and for its toxicity in vivo, supporting a double-receptor model for this toxin.
肉毒神经毒素（BoNTs）包括七种细菌毒素（BoNT/A-G），它们靶向突触前末梢，并作为蛋白酶切割突触小泡胞吐所需的蛋白质。在这里，我们鉴定出突触小泡蛋白 SV2 是 BoNT/D 的蛋白受体。BoNT/D 通过突触小泡再循环进入培养的海马神经元，并且可以在脑洗涤剂提取物中结合 SV2。缺乏 SV2 的神经元不能结合和进入 BoNT/D，而 SV2 的三种同工型（SV2A/B/C）之一的表达可以挽救这种情况。SV2 在质膜上的定位介导了 BoNT/D 在神经元和 HEK293 细胞中的结合。此外，包含 BoNT/A 和 E 的结合位点的嵌合受体，这两种其他使用 SV2 作为受体的 BoNTs，不能介导 BoNT/D 的进入，这表明 BoNT/D 通过不同于 BoNT/A 和 E 的机制结合 SV2。最后，我们证明神经节苷脂对于 BoNT/D 进入神经元的结合和进入以及其在体内的毒性是必不可少的，支持了这种毒素的双受体模型。
