N-terminal Acetylation Stabilizes N-terminal Helicity in Lipid- and Micelle-bound α-Synuclein and Increases Its Affinity for Physiological Membranes
N-terminal Acetylation Stabilizes N-terminal Helicity in Lipid- and Micelle-bound α-Synuclein and Increases Its Affinity for Physiological Membranes
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DOI：
10.1074/jbc.m113.512459
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发表时间：
2014-02-07
影响因子：
4.8
通讯作者：
Eliezer, David
中科院分区：
文献类型：
--
作者：
Dikiy, Igor;Eliezer, David
背景：帕金森病蛋白-突触核蛋白的正常N-末端乙酰化的功能效应尚不清楚。结果：N-乙酰化稳定了膜结合型突触核蛋白N端的螺旋结构，包括一种新的部分螺旋状态。结论：螺旋度的稳定增加了膜对类似突触囊泡的亲和力。意义：在体内，突触核蛋白的N-乙酰化可能影响其生理功能和功能障碍。帕金森病蛋白-突触核蛋白是N-末端乙酰化的，但大多数体外研究都是使用未乙酰化的突触核蛋白。与脂膜的结合被认为是-突触核蛋白功能仍鲜为人知的关键。我们报道了N-末端乙酰化对突触核蛋白与不同组成和曲率的脂泡以及由去污剂辛基葡萄糖苷(BOG)和十二烷基硫酸钠(SDS)组成的胶束结合的影响。在十二烷基硫酸钠的存在下，N-末端的乙酰化导致N-末端大约10个残基的螺旋度略有增加，这可能是由于N-末端通过形成螺旋帽基序稳定了N-末端的磨损。在BOG的存在下，N-末端乙酰化的蛋白质采用了一种新的构象，其中N-末端约30个残基以部分螺旋构象与洗涤剂胶束结合，而蛋白质的其余部分保持未结合和无序。N-末端乙酰化对高负电荷含量的脂泡的结合基本没有影响，但与低负电荷含量的脂泡的结合增加，其中高曲率的脂泡结合更强。因此，自然产生的N末端乙酰化形式的突触核蛋白在其N端表现出稳定的螺旋性，并增加了对类似突触小泡的脂泡的亲和力，突触小泡是蛋白质在体内的结合靶标。此外，N末端乙酰化突触核蛋白的新型沼泽结合状态可能作为部分螺旋膜结合中间体的模型，在突触核蛋白的功能和功能障碍中发挥作用。
Background: The functional effects of normal N-terminal acetylation of the Parkinson disease protein -synuclein are unknown. Results:N-Acetylation stabilizes helical structure at the N terminus of membrane-bound forms of synuclein, including a novel partly helical state. Conclusion: Stabilization of helicity increases affinity for membranes similar to synaptic vesicles. Significance:In vivo N-acetylation of -synuclein likely affects its physiological function and dysfunction.The Parkinson disease protein -synuclein is N-terminally acetylated, but most in vitro studies have been performed using unacetylated -synuclein. Binding to lipid membranes is considered key to the still poorly understood function of -synuclein. We report the effects of N-terminal acetylation on -synuclein binding to lipid vesicles of different composition and curvature and to micelles composed of the detergents -octyl-glucoside (BOG) and SDS. In the presence of SDS, N-terminal acetylation results in a slightly increased helicity for the N-terminal approximate to 10 residues of the protein, likely due to the stabilization of N-terminal fraying through the formation of a helix cap motif. In the presence of BOG, a detergent used in previous isolations of helical oligomeric forms of -synuclein, the N-terminally acetylated protein adopts a novel conformation in which the N-terminal approximate to 30 residues bind the detergent micelle in a partly helical conformation, whereas the remainder of the protein remains unbound and disordered. Binding of -synuclein to lipid vesicles with high negative charge content is essentially unaffected by N-terminal acetylation irrespective of curvature, but binding to vesicles of lower negative charge content is increased, with stronger binding observed for vesicles with higher curvature. Thus, the naturally occurring N-terminally acetylated form of -synuclein exhibits stabilized helicity at its N terminus and increased affinity for lipid vesicles similar to synaptic vesicles, a binding target of the protein in vivo. Furthermore, the novel BOG-bound state of N-terminally acetylated -synuclein may serve as a model of partly helical membrane-bound intermediates with a role in -synuclein function and dysfunction.