Oligomerization and Membrane-binding Properties of Covalent Adducts Formed by the Interaction of α-Synuclein with the Toxic Dopamine Metabolite 3,4-Dihydroxyphenylacetaldehyde (DOPAL)
Oligomerization and Membrane-binding Properties of Covalent Adducts Formed by the Interaction of α-Synuclein with the Toxic Dopamine Metabolite 3,4-Dihydroxyphenylacetaldehyde (DOPAL)
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DOI：
10.1074/jbc.m115.686584
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发表时间：
2015-11-13
影响因子：
4.8
通讯作者：
Eliezer, David
中科院分区：
文献类型：
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作者：
Follmer, Cristian;Coelho-Cerqueira, Eduardo;Eliezer, David
多巴胺的氧化脱氨作用产生剧毒的醛类物质3,4 - 二羟基苯乙醛（DOPAL），在帕金森病患者的尸检大脑中发现其生成量增加。当将DOPAL注射到大鼠大脑的黑质中时，它会导致多巴胺能神经元的丧失，同时伴有突触前蛋白α - 突触核蛋白（αS）潜在有毒的寡聚体的积累，这可能解释了所描述的多巴胺代谢和αS聚集的协同毒性。在这项工作中，我们证明DOPAL除了导致蛋氨酸残基氧化为蛋氨酸亚砜外，还通过与赖氨酸残基形成席夫碱和迈克尔加成加合物与αS相互作用。DOPAL修饰导致可能由DOPAL交联的小αS寡聚体的形成。单体和寡聚体DOPAL加合物都强烈抑制未修饰的αS形成成熟的淀粉样纤维。αS与脂质囊泡或洗涤剂胶束的结合会使其N - 末端脂质结合结构域获得α - 螺旋结构，从而保护蛋白质免受DOPAL加合物的形成，进而抑制DOPAL诱导的αS寡聚化。在功能上，与未修饰的蛋白质相比，αS - DOPAL单体对脂质组成类似于突触囊泡的小单层囊泡的亲和力降低，并且膜诱导的α - 螺旋含量减少。这些结果表明，DOPAL可能会通过影响αS与脂质膜的相互作用，从而影响其在神经元中对突触囊泡运输的调节作用，即使在没有蛋白质寡聚化的情况下也会损害αS的功能。
Oxidative deamination of dopamine produces the highly toxic aldehyde 3,4-dihydroxyphenylacetaldehyde (DOPAL), enhanced production of which is found in post-mortem brains of Parkinson disease patients. When injected into the substantia nigra of rat brains, DOPAL causes the loss of dopaminergic neurons accompanied by the accumulation of potentially toxic oligomers of the presynaptic protein alpha-synuclein (aS), potentially explaining the synergistic toxicity described for dopamine metabolism and aS aggregation. In this work, we demonstrate that DOPAL interacts with aS via formation of Schiff-base and Michael-addition adducts with Lys residues, in addition to causing oxidation of Met residues to Met-sulfoxide. DOPAL modification leads to the formation of small aS oligomers that may be cross-linked by DOPAL. Both monomeric and oligomeric DOPAL adducts potently inhibit the formation of mature amyloid fibrils by unmodified aS. The binding of aS to either lipid vesicles or detergent micelles, which results in a gain of alpha-helix structure in its N-terminal lipid-binding domain, protects the protein against DOPAL adduct formation and, consequently, inhibits DOPAL-induced aS oligomerization. Functionally, aS-DOPAL monomer exhibits a reduced affinity for small unilamellar vesicles with lipid composition similar to synaptic vesicles, in addition to diminished membrane-induced alpha-helical content in comparison with the unmodified protein. These results suggest that DOPAL could compromise the functionality of aS, even in the absence of protein oligomerization, by affecting the interaction of aS with lipid membranes and hence its role in the regulation of synaptic vesicle traffic in neurons.