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的基本特性进行了广泛的研究，DNA和RNA是所有生物体的共享遗传物质。特别是，我们对RNA/DNA的催化特性感兴趣。定义可用于RNA和DNA酶（核酶和dnazymes）的催化范围对于理解早期生物催化系统在地球上的发展至关重要。生物聚合物（DNA/RNA与蛋白质与蛋白质）如何应对特定的催化挑战？并且，用于获得强大的新试剂，这些试剂可用于疾病的生物传感器，治疗剂以及其他经常意外的用途。 在我的实验室中发现了RNA/DNA的两种非常有趣且意外的催化特性：（a）某些催化DNA（DNAZYMES）能够利用（在对人类DNA不有害的波长下）修复导致癌症的胸腺胺二聚体在DNA本身中。最近，我们成功地创建了能够使用可见光而不是紫外线的DNA修复活性的变体dnazymes。 （b）大量的RNA和DNA能够与血红素（一种重要且多功能的代谢辅助因子）形成紧密的复合物。这些DNA/RNA复合体令人惊讶地催化了通常与高度专业的血红素利用蛋白酶相关的关键氧化反应。 该提案有两个目标：第一个目标是剖析鸟嘌呤富含RNA和DNA的催化特性，该特性与血红素形成紧密的复合物。我们将精确地确定血红素核酶在结构和机械上如何复制血红素蛋白的性质；并且，如何设计血红素核酶来氧化“困难”底物。我们的第二个目标是对使用可见光来修复DNA中的胸腺二聚体病变的dnazymes进行体外选择，表征和实际利用。具体而言，我们将确定光溶酶dnazyme是否能像蛋白质对应物一样有效。另外，我们将设计与医学相关的光溶解酶dnazymes，可以局部应用于人体皮肤，以防止紫外线防止DNA损伤。