Molecular modeling of the membrane targeting of phospholipase C pleckstrin homology domains
Molecular modeling of the membrane targeting of phospholipase C pleckstrin homology domains
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DOI：
10.1110/ps.0358803
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发表时间：
2003-09
期刊：
影响因子：
8
通讯作者：
Shaneen Singh;D. Murray
中科院分区：
文献类型：
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作者：
Shaneen Singh;D. Murray
磷脂酶C（PLC）可逆地与膜结合以水解磷脂酰肌醇-4，5-二磷酸（PI[4，5]P2），并且包括四种主要类别：β、γ、δ和ε。大多数真核PLC含有单个N末端普列克底物蛋白同源（PH）结构域，其被认为在膜靶向中起重要作用。已经确定了来自PLCδ1的单个PLC PH结构域的结构;该PH结构域以高亲和力和立体特异性结合PI（4，5）P2，并且充当PH结构域功能的范例。然而，实验研究表明，不同PLC类的PH结构域表现出不同的膜相互作用模式，反映了它们的氨基酸序列的差异。为了阐明其差异膜结合特异性的结构基础，我们通过使用生物信息学工具模拟了所有哺乳动物PLC PH结构域的三维结构，并通过使用连续静电方法计算了它们的生物物理特性。我们的计算分析解释了大量的实验数据，为那些具有未知功能的PH结构域提供了预测，并指出了PLCδ1-PH结构中确定的典型脂质结合位点以外的区域的功能作用。特别是，我们的计算预测，（1）来自四个PLC类中的每一个的成员表现出与通常观察到的PH结构域相比明显不同的静电特征，（2）非特异性静电相互作用有助于PLCδ-，PLCγ-和PLCβ-PH结构域的膜定位，（3）磷酸化通过静电排斥调节PLCβ-PH与其效应子的相互作用。我们的分子模型的PH结构域从所有的PLC类清楚地表明，一个共同的结构折叠可以作为一个支架的广泛的表面特征和生物物理特性，支持独特的功能作用。
Phospholipases C (PLCs) reversibly associate with membranes to hydrolyze phosphatidylinositol‐4, 5‐bisphosphate (PI[4,5]P2) and comprise four main classes: β, γ, δ, and ε. Most eukaryotic PLCs contain a single, N‐terminal pleckstrin homology (PH) domain, which is thought to play an important role in membrane targeting. The structure of a single PLC PH domain, that from PLCδ1, has been determined; this PH domain binds PI(4,5)P2 with high affinity and stereospecificity and has served as a paradigm for PH domain functionality. However, experimental studies demonstrate that PH domains from different PLC classes exhibit diverse modes of membrane interaction, reflecting the dissimilarity in their amino acid sequences. To elucidate the structural basis for their differential membrane‐binding specificities, we modeled the three‐dimensional structures of all mammalian PLC PH domains by using bioinformatic tools and calculated their biophysical properties by using continuum electrostatic approaches. Our computational analysis accounts for a large body of experimental data, provides predictions for those PH domains with unknown functions, and indicates functional roles for regions other than the canonical lipid‐binding site identified in the PLCδ1‐PH structure. In particular, our calculations predict that (1) members from each of the four PLC classes exhibit strikingly different electrostatic profiles than those ordinarily observed for PH domains in general, (2) nonspecific electrostatic interactions contribute to the membrane localization of PLCδ‐, PLCγ‐, and PLCβ‐PH domains, and (3) phosphorylation regulates the interaction of PLCβ‐PH with its effectors through electrostatic repulsion. Our molecular models for PH domains from all of the PLC classes clearly demonstrate how a common structural fold can serve as a scaffold for a wide range of surface features and biophysical properties that support distinctive functional roles.