Molecular modeling studies of the Akt PH domain and its interaction with phosphoinositides
Molecular modeling studies of the Akt PH domain and its interaction with phosphoinositides
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DOI：
10.1021/jm000493i
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发表时间：
2001-03-15
影响因子：
7.3
通讯作者：
Kozikowski, AP
中科院分区：
文献类型：
--
作者：
Rong, SB;Hu, YH;Kozikowski, AP
丝氨酸-苏氨酸蛋白激酶Akt是磷脂酰肌醇3-激酶（PI 3-K）的直接下游靶标。PI 3-K产生的磷脂通过直接结合Akt PH结构域来调节Akt活性。PI 3-K产生的磷脂的结合是Akt重新定位到质膜的关键，这在Akt活化过程中起着重要作用。PI 3-K/Akt信号通路的激活促进细胞存活。为了阐明PI 3-K产生的磷脂与Akt PH结构域相互作用的结构基础，以进行基于结构的药物设计为目的，我们对Akt PH结构域的三维结构进行了建模。采用基于比较建模的方法，并使用建模的Akt结构，进而使用计算对接方法构建Akt与所选PIS-K生成的磷脂复合的结构模型。Akt PH结构域的模型由七条β-链组成，形成由C-末端α-螺旋加帽的两个反平行β-折叠。β 1-β 2、β 3-β 4和β 6-β 7环形成一个带正电的口袋，可以通过特定的氢键相互作用以互补的方式容纳PI 3-K产生的磷脂。残基Lys 14、Arg 25、Tyr 38、Arg 48和Arg 86形成结合口袋的底部，并特异性地与磷脂的3-和4-磷酸基团相互作用，而残基Thr 21和Arg 23位于结合口袋的壁上，并与1-磷酸基团结合。预测的结合模式与已知的定点诱变数据一致，其揭示了这些关键残基的突变导致Akt活性的丧失。此外，我们的模型可用于预测PI 3-K产生的磷脂的结合亲和力，并合理化Akt PH结构域对PI（3，4）P2的特异性，而不是其他磷脂如PI（3）P和PI（3，4，5）P3。总之，我们的建模研究提供了一个更好的理解Akt PH结构域和PIS-K产生的磷脂之间存在的分子相互作用，从而提供了一个坚实的结构基础，用于设计新的，高亲和力的配体调节Akt的活性。
The serine-threonine protein kinase Akt is a direct downstream target of phosphatidylinositol 3-kinase (PI3-K). The PI3-K-generated phospholipids regulate Akt activity via directly binding to the Akt PH domain. The binding of PI3-K-generated phospholipids is critical to the relocalization of Akt to the plasma membrane, which plays an important role in the process of Akt activation. Activation of the PI3-K/Akt signaling pathway promotes cell survival. To elucidate the structural basis of the interaction of PI3-K-generated phospholipids with the Akt PH domain with the objective of carrying out structure-based drug design, we modeled the three-dimensional structure of the Akt PH domain. Comparative modeling-based methods were employed, and the modeled Akt structure was used in turn to construct structural models of Akt in complex with selected PIS-K-generated phospholipids using the computational docking approach. The model of the Akt PH domain consists of seven beta -strands forming two antiparallel beta -sheets capped by a C-terminal alpha -helix. The beta1-beta2, beta3-beta4, and beta6-beta7 loops form a positively charged pocket that can accommodate the PI3-K-generated phospholipids in a complementary fashion through specific hydrogen-bonding interactions. The residues Lys14, Arg25, Tyr38, Arg48, and Arg86 form the bottom of the binding pocket and specifically interact with the 3- and 4-phophate groups of the phospholipids, while residues Thr21 and Arg23 are situated at the wall of the binding pocket and bind to the l-phosphate group. The predicted binding mode is consistent with known site-directed mutagenesis data, which reveal that mutation of these crucial residues leads to the loss of Akt activity. Moreover, our model can be used to predict the binding affinity of PI3-K-generated phospholipids and rationalize the specificity of the Akt PH domain for PI(3,4)P2, as opposed to other phospholipids such as PI(3)P and PI(3,4,5)P3. Taken together, our modeling studies provide an improved understanding of the molecular interactions present between the Akt PH domain and the PIS-K-generated phospholipids, thereby providing a solid structural basis for the design of novel, high-affinity ligands useful in modulating the activity of Akt.