Electrostatics and the membrane association of Src: Theory and experiment
Electrostatics and the membrane association of Src: Theory and experiment
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DOI：
10.1021/bi972012b
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发表时间：
1998-02-24
期刊：
影响因子：
2.9
通讯作者：
McLaughlin, S
中科院分区：
文献类型：
--
作者：
Murray, D;Matsumoto, LH;McLaughlin, S
Src与磷脂膜的结合需要将其肉豆蔻酸酯疏水插入膜的烃内部和其N-末端碱性残基簇与酸性磷脂的非特异性静电相互作用。我们提供了一个理论描述的静电分区Src到磷脂膜。具体而言，我们使用分子模型来表示对应于Src的残基2-19的非豆蔻酰化肽[nonmyr-Src（2-19）; GSSKSKPKDPSQRRSLE-NH 2]和磷脂双层，通过求解非线性Poisson-Boltzmann方程来计算静电相互作用，并使用统计热力学来预测摩尔分配系数。通过测量nonmyr-Src（2-19）在磷脂囊泡上的分配，理论预测与实验数据一致：膜结合随着囊泡中酸性脂质的摩尔百分比增加、溶液的离子强度降低或肽的净正电荷增加而增加。理论模型还正确预测了肉豆蔻酰化肽myr-Src（2-19）的测量分配;例如，向电中性囊泡中加入33%酸性脂质使myr-Src（2-19）的分配增加了100倍。磷酸化丝氨酸12（通过蛋白激酶C）或丝氨酸17（通过cAMP依赖性蛋白激酶）使myr-Src（2-19）在含有酸性脂质的囊泡上的分配减少10倍。我们研究了磷酸化对Src定位到生物膜的影响，通过在COS-1细胞中表达Src的N末端与可溶性载体蛋白的融合构建体;磷酸化产生Src嵌合体从质膜到胞质溶胶的分布的小转变。
The binding of Src to phospholipid membranes requires both hydrophobic insertion of its myristate into the hydrocarbon interior of the membrane and nonspecific electrostatic interaction of its N-terminal cluster of basic residues with acidic phospholipids. We provide a theoretical description of the electrostatic partitioning of Src onto phospholipid membranes. Specifically, we use molecular models to represent a nonmyristoylated peptide corresponding to residues 2-19 of Src [nonmyr-Src(2-19); GSSKSKPKDPSQRRSLE-NH2] and a phospholipid bilayer, calculate the electrostatic interaction by solving the nonlinear Poisson-Boltzmann equation, and predict the molar partition coefficient using statistical thermodynamics. The theoretical predictions agree with experimental data obtained by measuring the partitioning of nonmyr-Src(2-19) onto phospholipid vesicles: membrane binding increases as the mole percent of acidic lipid in the vesicles is increased, the ionic strength of the solution is decreased, or the net positive ch;uge of the peptide is increased. The theoretical model also correctly predicts the measured partitioning of the myristoylated peptide, myr-Src(2-19); for example, adding 33% acidic lipid to electrically neutral vesicles increases the partitioning of myr-Src(2-19) 100-fold. Phosphorylating either serine 12 (by protein kinase C) or serine 17 (by cAMP-dependent protein kinase) decreases the partitioning of myr-Src(2-19) onto vesicles containing acidic lipid 10-fold. We investigated the effect of phosphorylation on the localization of Src to biological membranes by expressing fusion constructs of Src's N terminus with a soluble carrier protein in COS-1 cells; phosphorylation produces a small shift in the distribution of the Src chimeras from the plasma membrane to the cytosol.