Ribozymes and DNAzymes-- ancient catalytic activities for modern biomedical and other utility

核酶和脱氧核糖核酸酶——现代生物医学和其他用途的古老催化活性

• 批准号: 105785-2012
• 负责人: Sen, Dipankar
• 金额: $ 5.17万
• 依托单位: Simon Fraser University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=569113
• 关键词: Ribozymes; DNAzymes; ancient; catalytic; activities

My laboratory conducts broad-ranging research on the fundamental properties of DNA and RNA, the shared genetic material of all living organisms. Particularly, we are interested in the catalytic properties of RNA/DNA. Defining the range of catalysis available to RNA and DNA enzymes (ribozymes and DNAzymes) is crucial for understanding how early bio-catalytic systems evolved on earth; how quite different biopolymers (DNA/RNA versus proteins) can meet specific catalytic challenges; and, for obtaining powerful new reagents that can be applied towards disease bio-sensing, therapeutics, as well as other, often unanticipated, uses. Two very interesting and unexpected catalytic properties of RNA/DNA have been discovered in my laboratory: (a) that certain catalytic DNAs (DNAzymes) are able to harness light (at wavelengths not harmful to human DNA) to repair cancer-causing thymine dimer lesions in DNA itself. We have recently succeeded in creating variant DNAzymes that are able to utilize visible rather than UV light for their DNA repair activity. And, (b) that large numbers of RNAs and DNAs are able to form tight complexes with heme, an important and versatile metabolic cofactor. These DNA/RNA-complexes then surprisingly catalyze key oxidative reactions, that are normally associated with highly specialized heme-utilizing protein enzymes. This proposal has two goals: The first will be to dissect the catalytic properties of guanine-rich RNAs & DNAs that form tight complexes with heme. We will determine precisely how heme-ribozymes structurally and mechanistically replicate the properties of heme proteins; and, how a heme-ribozyme could be designed to oxidize "difficult" substrates. Our second goal will be to conduct in vitro selection, characterization, and practical utilization of DNAzymes that use visible light to repair thymine dimer lesions in DNA. Specifically, we will determine whether a photolyase DNAzyme can ever be as efficient as its protein counterparts; also we will design medically relevant photolyase DNAzymes, that can be applied topically to human skin to offer protection against DNA damage by ultraviolet light.

我的实验室对DNA和RNA的基本性质进行了广泛的研究，DNA和RNA是所有生物体共有的遗传物质。特别是，我们对RNA/DNA的催化性质感兴趣。确定RNA和DNA酶（核酶和DNA酶）的催化范围对于理解早期生物催化系统如何在地球上进化至关重要;不同的生物聚合物（DNA/RNA与蛋白质）如何应对特定的催化挑战;以及获得强大的新试剂，可用于疾病生物传感，治疗，以及其他通常意想不到的用途。 我的实验室发现了RNA/DNA的两个非常有趣和意想不到的催化特性：（a）某些催化DNA（DNA酶）能够利用光（在对人类DNA无害的波长下）修复DNA本身中致癌的胸腺嘧啶二聚体损伤。我们最近成功地创造了能够利用可见光而不是紫外光进行DNA修复活动的变异DNA酶。和，（B）大量的RNA和DNA能够与血红素形成紧密的复合物，血红素是一种重要的和多功能的代谢辅因子。这些DNA/RNA复合物然后令人惊讶地催化关键的氧化反应，这通常与高度专门化的血红素利用蛋白酶有关。 这个提议有两个目标：第一个是剖析富含鸟嘌呤的RNA和DNA与血红素形成紧密复合物的催化特性。我们将精确地确定血红素核酶如何在结构上和机械上复制血红素蛋白的特性;以及血红素核酶如何被设计成氧化“困难”的底物。我们的第二个目标将是进行体外选择，表征和实际利用的DNA酶，使用可见光修复胸腺嘧啶二聚体损伤的DNA。具体来说，我们将确定光解酶DNA酶是否可以像其蛋白质对应物一样有效;我们还将设计医学相关的光解酶DNA酶，可以局部应用于人体皮肤，以保护免受紫外线对DNA的损伤。