Investigating the structural assembly of RNR multimers

研究 RNR 多聚体的结构组装

• 批准号: 8669995
• 负责人: Chris G Dealwis
• 金额: $ 29.38万
• 依托单位: CASE WESTERN RESERVE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-06-01 至 2016-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8669995
• 关键词: Affect; Allosteric Regulation; Allosteric Site; Antineoplastic Agents; Binding; Biochemical; Biological Assay; Catalysis; Catalytic Domain; Childhood Leukemia; Clofarabine; Complex; Cryoelectron Microscopy; Crystallization; Data; Data Reporting; Deoxyribonucleotides; Drug usage; Electron Microscopy; Enzymes; Equilibrium; Escherichia coli; Eukaryota; Free Radicals; Higher Order Chromatin Structure; Housing; Human; Laboratories; Lead; Life; Malignant neoplasm of pancreas; Maps; Mutation; Nucleotides; Outcome; Pharmaceutical Preparations; Physiological; Population; Preparation; RRM1 gene; Resolution; Ribonucleotide Reductase; Ribonucleotide Reductase Inhibitor; Ribonucleotides; Roentgen Rays; Saccharomyces cerevisiae; Scanning Transmission Electron Microscopy Procedures; Site-Directed Mutagenesis; Solutions; Structure; Sulfhydryl Compounds; X-Ray Crystallography; Yeasts; analytical ultracentrifugation; base; density; design; dimer; flexibility; gain of function; gemcitabine; improved; inhibitor/antagonist; insight; light scattering; mutant; particle; ribonucleotide reductase M2; stoichiometry; tool

DESCRIPTION (provided by applicant): Ribonucleotide reductase (RR) key to maintaining life as it catalyzes the slowest step in de novo DNTP synthesis by reducing ribonucleotides to deoxy ribonucleotides. RR is a multi-subunit enzyme consisting of a subunit that contains two allosteric sites and a catalytic site, and a b subunit that houses a free-radical that initiates thol-based catalysis. For almost 40 years RRs were thought to exist as heterotetramers. This organization failed, however, to explain how dATP inactivates and ATP activates the enzyme. Recently, this view has been challenged by biochemical data from other labs and structural data reported by us that support the existence of higher-order oligomers induced by its activator ATP and its inhibitor dATP. Interestingly, though ATP is an activator and dATP is an inhibitor of RR, they both cause the subunit to hexamerize. We propose that the two hexamers have different packing arrangements which lead to opposite outcomes of RR activity. Additionally, two important cancer drugs, gemcitabine and clofarabine are known to bind to higher-order RR oligomers. Thus, it is becoming increasingly clear that for an understanding of how RR is regulated in eukaryotes and targeted by cancer drugs, it is essential to elucidate the structure of higher-order oligomers formed by eukaryotic RRs. As higher-order holo-complexes may not be amenable to X-ray crystallography, we propose to use X-ray crystallography to determine the high-resolution structures of RR1 oligomers and single-particle electron microscopy (EM) to elucidate the organization of RR1 and RR2 in the holo-complexes.

描述（由申请人提供）：核糖核苷酸还原酶（RR）是维持生命的关键，因为它通过将核糖核苷酸还原为脱氧核糖核苷酸来催化从头DNTP合成中最慢的步骤。RR是一种多亚基酶，由一个含有两个变构位点和一个催化位点的亚基和一个含有引发thol基催化的自由基的B亚基组成。近40年来，RRs被认为是以异源四聚体的形式存在的。然而，该组织未能解释dATP如何使酶失活，而ATP如何使酶活化。最近，这一观点受到了来自其他实验室的生化数据和我们报道的结构数据的挑战，这些数据支持由其激活剂ATP和抑制剂dATP诱导的高阶寡聚体的存在。有趣的是，虽然ATP是RR的激活剂，dATP是RR的抑制剂，但它们都导致亚基六聚化。我们建议，这两个六聚体有不同的包装安排，导致相反的结果RR活动。此外，已知两种重要的癌症药物吉西他滨和氯法拉滨与高阶RR寡聚体结合。因此，越来越清楚的是，为了理解RR在真核生物中是如何调节的以及如何被癌症药物靶向，阐明RR的结构是至关重要的。 由真核生物RR形成的高阶寡聚体。由于高阶全息复合物可能不适合X射线晶体学，我们建议使用X射线晶体学来确定RR1低聚物的高分辨率结构和单粒子电子显微镜（EM）来阐明全息复合物中RR1和RR2的组织。