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损伤的生物化学机制在维持基因组完整性并从而预防正常细胞中的癌症方面起着核心作用，但它也限制了DNA损伤剂的功效，这些DNA损伤剂代表了临床肿瘤学中最广泛使用和最成功的化疗药物。因此，对DNA修复酶的酶促反应机制和生理功能的详细了解代表了关于正常细胞功能和保护它们免受致癌转化的系统的基本知识。然而，这一知识在改善癌症治疗的努力中也是实际重要的，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，AlkB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直接修复腺嘌呤和胞嘧啶碱基，这些碱基已在内环氮原子上烷基化，这是一种由内源性和环境诱变剂介导的毒性DNA修饰。AlkB催化的化学反应的阐明使得在理解其生理功能方面取得了快速进展，除了修复DNA中的诱变损伤之外，还包括修复降低翻译效率的受损mRNA和tRNA分子。然而，许多功能的AlkB超家族酶仍然是其特征，包括结构机制，使混杂识别不同的底物，其催化反应机制的细节，和生物功能的8个不同的序列同源物是保守的哺乳动物生物体。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AlkB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.