Interactions of the GM2 activator protein with phosphatidylcholine bilayers: a site-directed spin-labeling power saturation study.
Interactions of the GM2 activator protein with phosphatidylcholine bilayers: a site-directed spin-labeling power saturation study.
复制标题
GM2 激活蛋白与磷脂酰胆碱双层的相互作用：定点自旋标记功率饱和研究。
DOI：
10.1016/j.bpj.2009.05.058
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发表时间：
2009
影响因子：
3.4
通讯作者：
Fanucci,GailE
中科院分区：
文献类型：
--
作者：
Mathias,JordanD;Ran,Yong;Carter,JefferyD;Fanucci,GailE
GM 2激活蛋白（GM 2AP）是一种辅助蛋白，是神经节苷脂GM 2的催化剂中的必需组分。GM 2AP的功能是结合并从溶酶体内囊泡中提取GM 2，形成可溶性蛋白质-脂质复合物，其与水解酶氨基己糖苷酶A相互作用，该酶切割GM 2的末端糖基。在这里，我们使用的功率饱和电子顺磁共振定点自旋标记，以确定磷脂酰胆碱囊泡的表面结合的取向GM 2AP。由于GM 2AP提取脂质配体从囊泡和正在进行交换和关闭的囊泡表面，我们利用镍螯合脂质本地化的顺磁性金属碰撞到脂质双层-水界面。与脂质结合的金属松弛剂碰撞的自旋标记位点提供了用于映射与脂质双层界面相互作用的蛋白质位点的手段。结果表明，GM 2AP结合到脂质双层，使得内衬脂质结合腔的残基位于囊泡表面上。这种取向创造了有利的微环境，可以允许脂质尾部从双层直接翻转到GM 2AP的疏水口袋中。
The GM2 activator protein (GM2AP) is an accessory protein that is an essential component in the catabolism of the ganglioside GM2. A function of GM2AP is to bind and extract GM2 from intralysosomal vesicles, forming a soluble protein-lipid complex, which interacts with the hydrolase Hexosaminidase A, the enzyme that cleaves the terminal sugar group of GM2. Here, we used site-directed spin labeling with power saturation electron paramagnetic resonance to determine the surface-bound orientation of GM2AP upon phosphatidylcholine vesicles. Because GM2AP extracts lipid ligands from the vesicle and is undergoing exchange on and off the vesicle surface, we utilized a nickel-chelating lipid to localize the paramagnetic metal collider to the lipid bilayer-aqueous interface. Spin-labeled sites that collide with the lipid-bound metal relaxing agent provide a means for mapping sites of the protein that interact with the lipid bilayer interface. Results show that GM2AP binds to lipid bilayers such that the residues lining the lipid-binding cavity lie on the vesicle surface. This orientation creates a favorable microenvironment that can allow for the lipid tails to flip out of the bilayer directly into the hydrophobic pocket of GM2AP.