Structural Biology of Miz-1 and of C2H2 Zinc Fingers

在本研究项目中，我们的目标是阐明多趾基C2H2锌指转录因子mz -1的结构生物学。我们将重点研究mz -1与细胞周期抑制剂p15INK4b （p15）和p21CIP1 （p21）的核心启动子之间的相互作用。mz -1直接与这些核心启动子结合并激活p15和p21的转录。人类基因组中编码多趾酰基C2H2 ZF蛋白的基因超过700个，平均每个基因有8个。C2H2 zf是一种小的模块结构域（约30个残基），已知参与基因启动子中DNA碱基的三联体识别。另一方面，越来越多的证据表明，C2H2 ZFs也参与蛋白质之间的相互作用。有一个关于多趾型ZF转录因子功能的新范式，这意味着ZF的亚群参与DNA结合，其他亚群参与蛋白质-蛋白质相互作用。mz -1具有13个C2H2 ZFs一致序列，并且根据这一新范式，已经表明其前4个ZFs可以与Smad3结合，从而促进p15和p21的转录激活。另一方面，目前尚不清楚哪些zf与p15和p21核心启动子结合。在这种情况下，使用dna酶I足迹、电泳迁移率转移测定、核磁共振、等温滴定量热法和原子力显微镜等技术，我们建议确定：1- 13个mz -1 ZFs中哪一个与p15和p21核心启动子特异性相互作用，2- ZFs 1至4和11至13（我们已经解决了5-10）以及同源ZF/DNA复合物的NMR溶液结构，3-阐明ZFs 1至4与Smad3之间的相互作用模式，4-研究mz -1结合对p15和p21核心启动子拓扑结构的影响。该研究项目将对mz -1和C2H2 ZF的结构生物学产生重大影响，并有助于验证多dactyl C2H2 ZF TFs功能的新机制。它也将为我们理解p15和p21的转录调控提供重要的新视角，p15和p21是细胞周期中最重要的两个基因。****************************

In this research program, we aim to contribute to the elucidation of the structural biology the polydactyl C2H2 Zinc Finger Transcription Factor Miz-1. We will focus on the interaction between Miz-1 and the core promoters of the cell cycle inhibitors p15INK4b (p15) and p21CIP1 (p21). Miz-1 binds directly to these core promoters and activates the transcription of p15 and p21. More than 700 genes code for polydactyl C2H2 ZF proteins in the human genome with an average of 8 per gene. C2H2 ZFs are small modular domains (~30 residues) known to be involved in the recognition of triplets of DNA bases in gene promoters. On the other hand, there is an increasing body of evidence demonstrating that C2H2 ZFs are also involved in protein-protein interactions. There is an emerging paradigm for the function of polydactyl ZF transcription factors, which implies that subsets of ZFs are involved in DNA binding and others are involved in protein-protein interaction. Miz-1 possesses 13 C2H2 ZFs consensus sequences and in accordance with this new paradigm, it has been show that its first 4 ZFs can bind to Smad3 to contribute in the activation of the transcription of p15 and p21. On the other hand, it is not known which ZFs bind to the p15 and p21 core promoters. In this context and using techniques such as Dnase I footprinting, Electrophoretic Mobility Shift Assays, Nuclear Magnetic Resonance, Isothermal Titration Calorimetry and Atomic Force Microscopy, we propose to determine: 1- Which of the 13 Miz-1 ZFs interact specifically with the p15 and p21 core promoters, 2- The NMR solution structure of ZFs 1 to 4 and 11 to 13 (we have already solved 5-10) and of the cognate ZF/DNA complexes, 3- Elucidate the mode of interaction between ZFs 1 to 4 and Smad3 and 4- investigate of the effect of the binding of Miz-1 on the topology of the p15 and p21 core promoters. This research program will have a significant impact on the structural biology of Miz-1 and C2H2 ZF in general and contribute to validate of a new mechanism for the function of polydactyl C2H2 ZF TFs. It will also shed crucial new light into our understanding of the transcriptional regulation of p15 and p21, arguably, two of the most important genes in the cell cycle.****************************