Structure, mechanism, and inhibition of AlkB homologues

描述(申请人提供)：DNA修复被认为是肿瘤生物学的双刃剑。虽然修复DNA损伤的生化机制在维持基因组完整性从而预防正常细胞中的癌症方面发挥着核心作用，但它也限制了DNA损伤剂的疗效，这些药物代表了临床肿瘤学中一些最广泛使用和最成功的化疗药物。因此，对DNA修复酶的酶反应机制和生理功能的详细了解对于了解正常细胞的功能和保护它们免受致癌转化的系统具有重要的基础知识。然而，这一知识在改进癌症治疗的努力中也非常重要，因为DNA修复酶的抑制剂可以增强其他治疗剂的效力。最近，关于AlkB超家族中DNA修复酶的分子功能的知识激增，该超家族存在于所有真细菌和所有高等真核生物中。这些酶已被证明催化内环氮原子上烷基化的腺嘌呤和胞嘧啶碱基的直接修复，这是一种由内源和环境诱变剂介导的有毒DNA修饰。AlkB催化的化学反应的阐明使人们在理解它们的生理功能方面取得了快速进展，包括修复受损的mRNA和tRNA分子，这些分子降低了翻译效率，还修复了DNA的突变损伤。然而，AlkB超家族酶的许多特征仍有待研究，包括使不同底物混杂识别的结构机制，其催化反应机制的细节，以及哺乳动物生物中保守的8个不同序列同源物的生物学功能。我们计划应用生物物理、化学和分子生物学技术的组合来回答这些关于碱性B家族DNA修复酶的生物化学的基本问题。

DESCRIPTION (provided by applicant): DNA repair is considered the double-edged sword of tumor biology. While the biochemical machinery that repairs DNA damage plays a central role in maintaining genomic integrity and thereby preventing cancer in normal cells, it also limits the efficacy of the DNA-damaging agents that represent some of the most widely used and successful chemotherapeutic drugs in clinical oncology. Therefore, a detailed understanding of the enzymatic reaction mechanisms and physiological functions of DNA repair enzymes represents essential basic knowledge concerning the function of normal cells and the systems that protect them from oncogenic transformation. However, this knowledge is also practically important in efforts to improve cancer therapy because inhibitors of DNA repair enzymes can potentiate the potency of other therapeutic agents. Recently, there has been an explosion of knowledge concerning the molecular function of the DNA repair enzymes in the AlkB superfamily, which are present in all eubacteria and all higher eukaryotes. These enzymes have been shown to catalyze direct repair of adenine and cytosine bases that have been alkylated on endocyclic ring nitrogen atoms, a toxic DNA modification that is mediated by both endogenous and environmental mutagens. Elucidation of the chemical reaction catalyzed by AlkB has enabled rapid progress to be made in understanding their physiological function, which includes repair of damaged mRNA and tRNA molecules that reduce translation efficiency in addition to repair of mutagenic lesions in DNA. However, numerous features of AlkB superfamily enzymes remain to be characterized, including the structural mechanisms enabling promiscuous recognition of different substrates, the details of their catalytic reaction mechanism, and the biological function of the 8 distinct sequence homologues that are conserved in mammalian organisms. We plan to apply a combination of biophysical, chemical, and molecular biological techniques to answer these fundamental questions concerning the biochemistry of AlkB-family DNA repair enzymes.