A frequent kinase domain mutation that changes the interaction between PI3Kα and the membrane
A frequent kinase domain mutation that changes the interaction between PI3Kα and the membrane
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DOI：
10.1073/pnas.0908444106
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发表时间：
2009-10-06
影响因子：
11.1
通讯作者：
Amzel, L. Mario
中科院分区：
文献类型：
--
作者：
Mandelker, Diana;Gabelli, Sandra B.;Amzel, L. Mario
癌基因突变通常通过改变编码蛋白质的构象，从而改变酶活性来促进肿瘤发生。PIK 3CA癌基因编码磷脂酰肌醇3-激酶α（PI 3 K α）的催化亚基p110 α，是人类癌症中两种最常突变的癌基因之一。我们报告的结构最常见的突变体p110 α在复杂的两个相互作用的结构域，其监管伙伴（p85 α），无论是自由和约束的抑制剂（渥曼青霉素）。p85 α的N-末端SH 2（nSH 2）结构域显示形成整个酶复合物的支架，战略性地定位以将外源信号从磷酸肽传递到p110 α的三个不同区域。此外，我们发现Arg-1047指向细胞膜，垂直于WT酶中His-1047的方向。令人惊讶的是，在致癌突变体中，与细胞膜接触的激酶结构域的两个环改变了构象。生化分析表明，p110 α His 1047 Arg突变体的酶活性差异调节的脂质膜组合物。这些结构和生化数据表明，以前未描述的机制突变激活的激酶，涉及干扰其与细胞膜的相互作用。
Mutations in oncogenes often promote tumorigenesis by changing the conformation of the encoded proteins, thereby altering enzymatic activity. The PIK3CA oncogene, which encodes p110 alpha, the catalytic subunit of phosphatidylinositol 3-kinase alpha (PI3K alpha), is one of the two most frequently mutated oncogenes in human cancers. We report the structure of the most common mutant of p110 alpha in complex with two interacting domains of its regulatory partner (p85 alpha), both free and bound to an inhibitor (wortmannin). The N-terminal SH2 (nSH2) domain of p85 alpha is shown to form a scaffold for the entire enzyme complex, strategically positioned to communicate extrinsic signals from phosphopeptides to three distinct regions of p110 alpha. Moreover, we found that Arg-1047 points toward the cell membrane, perpendicular to the orientation of His-1047 in the WT enzyme. Surprisingly, two loops of the kinase domain that contact the cell membrane shift conformation in the oncogenic mutant. Biochemical assays revealed that the enzymatic activity of the p110 alpha His1047Arg mutant is differentially regulated by lipid membrane composition. These structural and biochemical data suggest a previously undescribed mechanism for mutational activation of a kinase that involves perturbation of its interaction with the cellular membrane.