A combinatorial code for the interaction of α-synuclein with membranes
A combinatorial code for the interaction of α-synuclein with membranes
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DOI：
10.1074/jbc.m504894200
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发表时间：
2005-09-09
影响因子：
4.8
通讯作者：
Fortin, DL
中科院分区：
文献类型：
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作者：
Kubo, S;Nemani, VM;Fortin, DL
大量的遗传和病理学证据表明，小的可溶性蛋白α-突触核蛋白在家族性和散发性帕金森病（PD）的发病机制中起作用。然而，α-突触核蛋白在疾病过程中的确切作用及其正常功能仍然知之甚少。我们最近发现，与脂筏的相互作用是至关重要的正常，突触前定位的α-突触核蛋白。为了了解α-突触核蛋白如何与脂筏相互作用，我们现在已经开发了一种体外结合试验，从天然膜纯化的筏。重述在体内观察到的特异性，重组野生型而不是PD相关的A30 P突变体α-突触核蛋白结合从培养的细胞和纯化的突触囊泡分离的脂筏。筏的蛋白水解消化不破坏α-突触核蛋白的结合，表明与脂质而不是这些膜的蛋白质组分的相互作用。我们还发现，α-突触核蛋白直接结合人工膜，其脂质组成模拟脂筏。α-突触核蛋白与这些筏状脂质体的结合需要酸性磷脂，优选磷脂酰丝氨酸（PS）。有趣的是，各种合成的PS与定义的酰基链不支持结合时，单独使用。相反，与α-突触核蛋白的相互作用需要PS与油酸（18：1）和多不饱和（20：4或22：6）脂肪酰基链的组合，这表明膜内的相分离的作用。此外，α-突触核蛋白以更高的亲和力与人工膜结合，其中PS头基在多不饱和脂肪酰基链上而不是在油酰基侧链上，表明α-突触核蛋白与膜相互作用的严格组合代码。
Considerable genetic and pathological evidence has implicated the small, soluble protein alpha-synuclein in the pathogenesis of familial and sporadic forms of Parkinsons disease (PD). However, the precise role of alpha-synuclein in the disease process as well as its normal function remain poorly understood. We recently found that an interaction with lipid rafts is crucial for the normal, pre-synaptic localization of alpha-synuclein. To understand how alpha-synuclein interacts with lipid rafts, we have now developed an in vitro binding assay to rafts purified from native membranes. Recapitulating the specificity observed in vivo, recombinant wild type but not PD-associated A30P mutant alpha-synuclein binds to lipid rafts isolated from cultured cells and purified synaptic vesicles. Proteolytic digestion of the rafts does not disrupt the binding of alpha-synuclein, indicating an interaction with lipid rather than protein components of these membranes. We have also found that alpha-synuclein binds directly to artificial membranes whose lipid composition mimics that of lipid rafts. The binding of alpha-synuclein to these raft-like liposomes requires acidic phospholipids, with a preference for phosphatidylserine ( PS). Interestingly, a variety of synthetic PS with defined acyl chains do not support binding when used individually. Rather, the interaction with alpha-synuclein requires a combination of PS with oleic ( 18: 1) and polyunsaturated ( either 20: 4 or 22: 6) fatty acyl chains, suggesting a role for phase separation within the membrane. Furthermore, alpha-synuclein binds with higher affinity to artificial membranes with the PS head group on the polyunsaturated fatty acyl chain rather than on the oleoyl side chain, indicating a stringent combinatorial code for the interaction of alpha-synuclein with membranes.