Mechanistic Studies of Ribonucleotide Reductase

Yeshiva大学阿尔伯特·爱因斯坦医学院的Gary Gerfen博士将在化学部生命过程化学项目的这一奖项中，研究核糖核苷三磷酸还原酶的周转和抑制机制。核糖核苷酸还原酶(RNRs)存在于所有细胞内的非寄生生物中，也是由许多DNA病毒编码的。这些酶催化核苷酸还原成相应的脱氧核糖核苷酸，这是DNA复制和修复前体从头生成的唯一已知方法。尽管最近对所有类型的RNR的研究都取得了重大进展，但关于底物周转的机制、机械抑制剂的失活和变构调节仍然存在问题。该奖项的目标是关注最简单的代表性RNR，来自莱氏乳杆菌的核糖核苷三磷酸还原酶(RTPR)。深入了解这种最简单的核糖核苷酸还原酶的反应机制和变构调节，将有助于对这类重要酶的基本理解。Gerfen博士将使用核糖核苷酸和活性位点突变来研究底物周转的机制，以及使用基于机制的抑制剂来研究抑制和失活的机制。最后，将利用室温连续波和低温脉冲位定向自旋标记电子顺磁共振技术来探索被认为对变构调节重要的RTPR区域的结构和动力学。核糖核苷酸还原酶是几乎所有生物体中唯一提供DNA构建块的酶。因为DNA对细胞功能的各个方面都至关重要，所以这些酶在从细菌到人类的有机体的新陈代谢中发挥着至关重要的作用。这些酶的结构和功能缺陷会导致许多疾病，目前临床上正在使用旨在抑制核糖核苷酸还原酶功能的抗菌和抗癌药物。然而，目前还不清楚使这些酶失活的药物是如何发挥作用的。Gerfen博士的工作将使我们更好地理解核苷酸还原酶发挥作用的基本机制。

In this award from the Chemistry of Life Processes Program in the Chemistry Division, Dr. Gary Gerfen, from the Albert Einstein College of Medicine of Yeshiva University, will investigate the mechanism of turnover by and inhibition of the enzyme ribonucleoside triphosphate reductase. Ribonucleotide reductases (RNRs) are present in all cellular non-parasitic organisms characterized to date, and are also encoded by many DNA viruses. These enzymes catalyze the reduction of nucleotides to the corresponding deoxyribonucleotides, the only known means of de novo generation of precursors for both DNA replication and repair. Despite significant progress being made in the study of all classes of RNR recently, questions remain regarding mechanisms of substrate turnover, inactivation by mechanistic inhibitors and allosteric regulation. The objective of this award is to focus on the simplest representative RNR, ribonucleoside triphosphate reductase (RTPR) from Lactobacillus leichmannii. Gaining insight into the reaction mechanism and allosteric regulation of this simplest of the ribonucleotide reductases will contribute to basic understanding of this important class of enzymes. Dr. Gerfen will investigate the mechanism of substrate turnover using ribonucleotides and active site mutants, and the mechanism of inhibition and inactivation using mechanism-based inhibitors. Finally, the structure and dynamics of regions of RTPR thought to be important for allosteric regulation will be probed using room temperature continuous wave and low temperature pulsed site directed spin label electron paramagnetic resonance techniques.Ribonucleotide reductases are enzymes that provide the only known way to make the building blocks of DNA in almost all organisms. Because DNA is crucial to every aspect of cellular function, these enzymes play an essential role in the metabolism of organisms from bacteria to humans. Defects in the structure and function of these enzymes lead to many diseases, and antibacterial and anticancer drugs designed to inhibit the function ribonucleotide reductases are currently in clinical use. However, it is not understood how the drugs that inactivate these enzymes function. Dr. Gerfen's work will give us better understanding of the basic mechanisms by which ribonucleotide reductases function.