Catalytic halogen bonds in enzymatic bond breaking and making in DNA

DNA 中酶促键断裂和形成中的催化卤素键

• 批准号: 2203161
• 负责人: Pui Ho
• 金额: $ 60万
• 依托单位: Colorado State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2203161&HistoricalAwards=false
• 关键词: Catalytic; halogen; bonds; enzymatic; bond

With this award, the Chemistry of Life Processes Program of the Chemistry Division is funding Professors Pui S. Ho and Anthony K. Rappé at Colorado State University to determine how halogens can replace magnesium in the design of catalytic proteins (enzymes) that break and make the bonds in DNA. Magnesium is the metal typically used by enzymes to help cut or join DNA in cells. Dr. Ho’s group has shown that the catalytic magnesium in an enzyme found in mice can be replaced by an unnatural chlorinated or iodinated amino acid. This project will determine how an interaction called halogen-bonding allows elements on opposite ends of the periodic table to catalyze the same DNA-modifying reactions. This science probes the idea of using halogen-bonding as a design tool to engineer synthetic enzymes for biotechnology applications. This project will provide training in structural and computational chemistry to graduate and undergraduate students, including those from underrepresented groups. Finally, an outreach project will help middle school and high school students learn how scientists use “X-ray vision” see the atoms in three dimensions in DNA and proteins.The making and breaking of the bonds along the DNA backbone are critical reactions in a broad range of genomic processes. Endonucleases and ligases typically use magnesium ion or similar metal cations as catalysts to specifically cut and rejoin DNA fragments. The Ho and Rappé groups have shown that the essential catalytic divalent magnesium ion in mouse endonuclease G (mEndoG) can be functionally replaced by a chlorinated or iodinated tyrosine. The resulting halogenated construct recapitulates the activity of the wild type mEndoG to specifically cleave four-stranded DNA Holliday junctions that contain a 5-hydroxymethylcytosine base. This cleavage reaction is catalyzed by a hydrogen bond (H-bond) enhanced halogen bond (X-bond), or HBeXB, for short. In addition, the halogenated enzyme was found to catalyze a unique ATP-independent DNA joining reaction that is also seen in the wild type mEndoG. This research project will characterize the structural and mechanistic properties that allow this metal-free, X-bond catalyzed enzyme (or cX-Zyme) to act as a site-specific endonuclease and an ATP-independent ligase. From a broad scientific perspective, this work raises the interesting possibility that one may be able to exploit X-bonding quite generally as a novel method to promote specific catalytic chemistry in enzyme active sites.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

凭借该奖项，化学系的生命过程化学项目正在资助科罗拉多州立大学的 Pui S. Ho 和 Anthony K. Rappé 教授，以确定卤素如何在催化蛋白质（酶）的设计中替代镁，从而分解和制造镁是酶通常用来帮助切割或连接细胞中 DNA 的金属，Ho 博士的研究小组已经证明，在小鼠体内发现的酶中的催化镁可以被替代。该项目将确定一种称为卤素键的相互作用如何使元素周期表两端的元素催化相同的 DNA 修饰反应。该项目将为研究生和本科生（包括来自弱势群体的学生）提供结构和计算化学方面的培训。最后，一个外展项目将帮助初中生和高中生。了解科学家如何使用“X 射线视觉”观察 DNA 和蛋白质中的三维原子。DNA 主链上的键的形成和断裂是广泛的基因组过程中的关键反应，通常使用镁离子。 Ho 和 Rappé 团队表明，小鼠核酸内切酶 G (mEndoG) 中必需的催化二价镁离子可以被功能性取代。所得到的卤化构建体概括了野生型 mEndoG 特异性切割含有 5-羟甲基胞嘧啶碱基的四链 DNA Holliday 连接的活性。该切割反应由氢键（H 键）催化。增强型卤键（X-键），简称HBeXB。另外，卤化酶是。发现能够催化独特的 ATP 独立 DNA 连接反应，这种反应也存在于野生型 mEndoG 中。该研究项目将表征这种无金属 X-bond 催化酶（或 cX-Zyme）的结构和机械特性。作为一种位点特异性核酸内切酶和一种不依赖于 ATP 的连接酶，从广泛的科学角度来看，这项工作提出了一种有趣的可能性，即人们可以非常普遍地利用 X-键合作为一种新方法。促进酶活性位点的特定催化化学。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。