MEMBRANE-BOUND CONFORMATION OF MASTOPARAN-X, A G-PROTEIN-ACTIVATING PEPTIDE
MEMBRANE-BOUND CONFORMATION OF MASTOPARAN-X, A G-PROTEIN-ACTIVATING PEPTIDE
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DOI：
10.1021/bi00139a032
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发表时间：
1992-06-23
期刊：
影响因子：
2.9
通讯作者：
HIGASHIJIMA, T
中科院分区：
文献类型：
--
作者：
WAKAMATSU, K;OKADA, A;HIGASHIJIMA, T
Mastoparan-X是黄蜂毒液中的一种十四肽，通过直接激活与磷脂酶C偶联的GTP结合调节蛋白(G蛋白)而引起各种细胞的分泌，其激活机制已被证明与体外G蛋白偶联受体非常相似，并且与膜的相互作用对于膜结合的G蛋白的激活似乎是非常重要的[Higashijima，T.，Uzu，S.，Nakajima，T.，&Ross，E.M.(1988)J.Biol]。化学。263、6491-6494]。我们报道了在全氚磷脂囊泡存在的情况下，通过转移核Overhauser效应的二维H-1-核磁共振分析，结合距离几何和分子动力学计算，确定了mastoparan-X的精确囊泡结合构象。在14个氨基酸残基中，C端的12个残基与磷脂双层结合后呈α-螺旋构象。α-螺旋的整体结构是两亲性的，一侧有三个赖氨酸侧链，另一侧有疏水侧链。这种构象在凝胶和膜的液晶相中都保持不变。本文所描述的构象将为理解作为G蛋白激活剂的马斯多兰类似物的构象-活性关系提供有用的基础。这些研究将有助于设计新的有效的类似物来调节G蛋白，并分析受体-G蛋白的相互作用。
Mastoparan-X, a tetradecapeptide from wasp venom, has been proposed to cause secretion from various kinds of cells by the direct activation of GTP-binding regulatory proteins (G proteins) that couple to phospholipase C. The mechanism of the activation has been shown to be very similar to that of G-protein-coupled receptors in vitro, and the interaction with membranes seems to be very important for the activation of G proteins that are membrane-bound [Higashijima, T., Uzu, S., Nakajima, T., & Ross, E. M. (1988) J. Biol. Chem. 263, 6491-6494]. We report here the precise vesicle-bound conformation of mastoparan-X in the presence of perdeuterated phospholipid vesicles, determined by two-dimensional H-1-NMR analyses of transferred nuclear Overhauser effects, combined with distance geometry and molecular dynamics calculations. Of 14 amino acid residues, the C-terminal 12 residues take an alpha-helical conformation upon binding to the phospholipid bilayer. The overall structure of the alpha-helix is amphiphilic, with three lysine side chains located on one side and with hydrophobic side chains on the other side. This conformation of mastoparan-X was maintained both in the gel and in the liquid-crystalline phases of the membranes. The conformation described herein will provide a useful basis for understanding conformation-activity relationships of mastoparan analogs as activators of G proteins. These studies will help to design novel potent analogs for the regulation of G proteins and to analyze receptor-G-protein interactions.