Protein-protein interactions during cell-cycle control: The human oncoprotein gankyrin and GADD45gamma

本项目旨在对人类肿瘤蛋白gankyrin和人类生长阻滞和DNA损伤反应蛋白GADD45γ进行生化和晶体学研究。Gankyrin是第一个与肝细胞癌直接相关的基因产物，并被描述为与视网膜母细胞瘤蛋白（Rb）、细胞周期蛋白依赖性蛋白激酶CDK4和CDK6、黑色素瘤抗原A4 （MAGE-A4）、26S蛋白酶体的S6 atp酶和泛素连接酶Mdm2相互作用。GADD45γ的抗增殖活性是通过与DNA聚合酶δ加工因子PCNA、蛋白激酶MTK1和蛋白CRIF的分子相互作用介导的。在我们计划的生化和结构研究中，我们将重点研究gankyrin与CDK4和MAGE-A4的相互作用，以及GADD45γ与PCNA、MTK1和CRIF的相互作用。这些相互作用将被生物化学表征，映射到蛋白质的定义域，并通过共晶的x射线衍射分析可视化。Max delbrck中心筛选单元和莱布尼茨分子药理学研究所提供的小分子将被筛选其抑制gankyrin或GADD45γ参与的选定蛋白质相互作用的潜力，部分基于我们计划开发的基于共结晶的配体筛选方案。

This project aims at biochemical and crystallographic studies of the human oncoprotein gankyrin and the human growth arrest and DNA damage-responsive protein GADD45γ. Gankyrin is the product of the first gene directly linked to hepatocellular carcinoma and was described to interact with the retinoblastoma protein (Rb), the cyclin-dependent protein kinases CDK4 and CDK6, the melanoma antigen A4 (MAGE-A4), the S6 ATPase of the 26S proteasome and the ubiquitin ligase Mdm2. The antiproliferative activity of GADD45γ is mediated by molecular interactions with the DNA polymerase δ processivity factor PCNA, the protein kinase MTK1 and the protein CRIF. In our planned biochemical and structural studies, we will focus on interactions of gankyrin with CDK4 and MAGE-A4, as well as GADD45γ with PCNA, MTK1 and CRIF. These interactions will be biochemically characterized, mapped to defined domains of the proteins and visualized by X-ray diffraction analysis of co-crystals. Small molecules available at the Screening Unit of the Max Delbrück Center and the Leibniz Institute for Molecular Pharmacology will be screened for their potential to inhibit selected proteinprotein interactions in which gankyrin or GADD45γ are engaged, partly based on a protocol for co-crystallisation-based ligand screening which we plan to develop.