Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.
University of Chinese Academy of Sciences, Beijing, China.
J Biomol Struct Dyn. 2020 Mar;38(4):975-984. doi: 10.1080/07391102.2019.1591303. Epub 2019 Mar 21.
Inhibitor of apoptosis proteins (IAPs) are important regulators of apoptosis, and protein targets for the development of anti-cancer drugs. Cellular inhibitor of apoptosis protein-1 (cIAP1) is an important member of IAPs. Peptides or small-molecular antagonists can induce the dimerization, auto-ubiquitination, and proteasomal degradation of the cellular inhibitor of apoptosis protein-1 (cIAP1). While in the absence of antagonists, several mutations of the cIAP1 protein also lead to its dimerization and auto-ubiquitination. Even though the crystal structure of cIAP1 protein has been determined, the intrinsic mechanism of its dimerization remains unexplored. Accumulating evidence indicated that intrinsic conformational change existed during the binding of antagonists with cIAP1 protein, or introduction of mutations. To reveal this intrinsic conformational change, molecular dynamics simulations at microsecond scale were applied for the wild-type and mutant-type cIAP1 proteins. Compared to the crystal structure, significant conformational change was observed during the simulations, which could explain the importance of previously identified key mutations. To validate these findings revealed by our simulations, a new mutation D303A was constructed and the following native polyacrylamide gel electrophoresis (native-PAGE) assay observed a proportion of spontaneous dimerization, in comparison with the wild-type control. Taken together, these computational and experimental results revealed the intrinsic conformational change of cIAP1, which could not only explain previously identified key mutations, but also be exploited for further design and development of anti-tumor compounds that target the cIAP1 protein.Communicated by Ramaswamy H. Sarma.
凋亡抑制蛋白（IAPs）是细胞凋亡的重要调节因子，也是抗癌药物研发的蛋白质靶标。细胞凋亡抑制蛋白-1（cIAP1）是 IAPs 的重要成员。肽或小分子拮抗剂可诱导细胞凋亡抑制蛋白-1（cIAP1）的二聚化、自身泛素化和蛋白酶体降解。而在没有拮抗剂的情况下，cIAP1 蛋白的几种突变也会导致其二聚化和自身泛素化。尽管已经确定了 cIAP1 蛋白的晶体结构，但其二聚化的内在机制仍未被探索。越来越多的证据表明，在拮抗剂与 cIAP1 蛋白结合或引入突变时，存在内在构象变化。为了揭示这种内在构象变化，我们对野生型和突变型 cIAP1 蛋白进行了微秒级别的分子动力学模拟。与晶体结构相比，模拟过程中观察到明显的构象变化，这可以解释先前确定的关键突变的重要性。为了验证我们模拟结果的发现，构建了一个新的突变 D303A，并通过天然聚丙烯酰胺凝胶电泳（native-PAGE）实验观察到与野生型对照相比，自发二聚化的比例。总之，这些计算和实验结果揭示了 cIAP1 的内在构象变化，不仅可以解释先前确定的关键突变，还可以进一步设计和开发靶向 cIAP1 蛋白的抗肿瘤化合物。由 Ramaswamy H. Sarma 传达。
