铜稳态对大脑的功能至关重要,它的崩溃与许多脑部疾病有关。还已知铜与带负电荷的脂质相互作用,磷脂酰丝氨酸(PS),以及α-突触核蛋白,一种富含突触的易于聚集的蛋白质,在突触小泡对接和融合中起作用。然而,铜之间的相互作用,PS脂质,和α-突触核蛋白是未知的。在这里,我们报告了有关铜稳态和神经传递的这三种成分之间相互作用的详细且主要的动力学研究。我们发现,突触小泡模仿单层小泡(SUV)可以在毫秒内隔离任何多余的游离Cu2,在生理条件下,GSH可以以几乎恒定的速率将SUV上结合的Cu2还原为Cu。此外,我们发现SUV结合的Cu2不会影响野生型α-突触核蛋白与SUV之间的结合,但会影响N端乙酰化α-突触核蛋白与SUV之间的结合。相比之下,Cu2可以有效地从囊泡中置换两种类型的α-突触核蛋白。我们的结果表明,突触小泡可能介导大脑中的铜转移,铜可以通过调节α-突触核蛋白与突触小泡之间的相互作用参与突触小泡与质膜的对接。
Copper homeostasis is critical to the functioning of the brain, and its breakdown is linked with many brain diseases. Copper is also known to interact with the negatively charged lipid, phosphatidylserine (PS), as well as α-synuclein, an aggregation-prone protein enriched in the synapse, which plays a role in synaptic vesicle docking and fusion. However, the interplay between copper, PS lipid, and α-synuclein is not known. Herein, we report a detailed and predominantly kinetic study of the interactions among these three components pertinent to copper homeostasis and neurotransmission. We found that synaptic vesicle-mimicking small unilamellar vesicles (SUVs) can sequester any excess free Cu2+ within milliseconds, and bound Cu2+ on SUVs can be reduced to Cu+ by GSH at a nearly constant rate under physiological conditions. Moreover, we revealed that SUV-bound Cu2+ does not affect the binding between wild-type α-synuclein and SUVs but affect that between N-terminal acetylated α-synuclein and SUVs. In contrast, Cu2+ can effectively displace both types of α-synuclein from the vesicles. Our results suggest that synaptic vesicles may mediate copper transfer in the brain, while copper could participate in synaptic vesicle docking to the plasma membrane via its regulation of the interaction between α-synuclein and synaptic vesicle.