XAS OF THE MN(IV)/FE(IV) INTERMEDIATE OF RIBONUCLEOTIDE REDUCTASE IN C TRACHOMA

沙眼中核糖核苷酸还原酶 MN(IV)/FE(IV) 中间体的 XAS

• 批准号: 8170245
• 负责人: MICHAEL T. GREEN
• 金额: $ 0.03万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-05-01 至 2011-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8170245
• 关键词: Catalysis; Chlamydia trachomatis; Computer Retrieval of Information on Scientific Projects Database; Coupled; Cysteine; DNA; Deoxyribonucleotides; Electron Transport; Electrons; Escherichia coli; Funding; Grant; Human; Institution; Iron; Manganese; Molecular; Natural regeneration; Organism; Oxygen; Phenylalanine; Protons; Publications; Research; Research Personnel; Resources; Ribonucleotide Reductase; Ribonucleotides; Side; Source; Structure; Techniques; Trachoma; Tyrosine; United States National Institutes of Health; absorption; base; cofactor; density; pathogen; ribonucleotide reductase M2; theories; tyrosine radical

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Ribonucleotide reductases (RNR) are essential to cellular organisms. They reduce ribonucleotides to deoxyribonucleotides and provide the building blocks of deoxyribonucleic acids (DNA). RNRs are divided into three different classes based on the mechanism they use for ribonucleotide reduction. Much research has been done on class I RNRs which include ribonucleotide reductase from humans and E. coli. Originally all class I RNRs were believed to utilize a diiron center and an ?essential? tyrosine radical to initiate proton coupled electron transfer. The proton coupled electron transfer generates a cysteine radical in R1 to begin ribonucleotide reduction. However, the human pathogen Chlamydia trachomatis (Ct) lacked the ?essential? tyrosine and had a phenylalanine in its place. It was later discovered by Jiang et al. that the R2 subunit of RNR from Ct featured a manganese and an iron instead of a diiron center and a tyrosine. In Ct R2 the heterobinuclear center starts as a Mn(II)/Fe(II) which is oxidized by molecular oxygen (O2) to the Mn(IV)/Fe(IV) intermediate. This intermediate is then reduced by one electron to form the active Mn(IV)/Fe(III) state. The Mn(IV)/Fe(III) cluster can initiate the proton coupled electron transfer to form the cysteine radical in R1 reducing the heterobinuclear center to the Mn(III)/Fe(III) state. The Mn(III)/Fe(III) state can be regenerated to the Mn(IV)/Fe(III) state for further catalysis. In a previous publication we (Younker et al.) utilized the heterobinuclear center of Ct R2 and characterized the structure of the Mn(IV)/Fe(III) cofactor utilizing extended x-ray absorption fine structure (EXAFS) from both the Mn and Fe sides and density functional theory (DFT) calculations. We now wish to utilize these same techniques to structurally characterize the Mn(IV)/Fe(IV) intermediate.

该副本是利用众多研究子项目之一 由NIH/NCRR资助的中心赠款提供的资源。子弹和 调查员（PI）可能已经从其他NIH来源获得了主要资金， 因此可以在其他清晰的条目中代表。列出的机构是 对于中心，这不一定是调查员的机构。 核糖核苷酸还原酶（RNR）对于细胞生物至关重要。 它们将核糖核苷酸降低至脱氧核糖核苷酸，并提供脱氧核糖核酸（DNA）的基础。 根据它们用于核糖核苷酸还原的机制，将RNR分为三个不同的类。 对I类RNR进行了许多研究，其中包括来自人类和大肠杆菌的核糖核苷酸还原酶。 最初，所有I级RNR都被认为使用二龙中心和一个“必需”中心？酪氨酸自由基启动质子耦合电子转移。 质子耦合电子转移在R1中产生半胱氨酸自由基，开始还原核糖核苷酸。 但是，人类病原体沙眼（CT）缺乏“必需”？酪氨酸，并在其位置有苯丙氨酸。 后来被江等发现。 CT的R2子单元具有锰和铁，而不是二龙中心和酪氨酸。在CT R2中，杂核中心以Mn（II）/Fe（II）的速度开始，该中心用分子氧（O2）氧化为Mn（IV）/Fe（IV）中级。 然后通过一个电子降低该中间体，形成活性Mn（IV）/Fe（III）状态。 Mn（IV）/Fe（III）簇可以启动质子耦合的电子转移，以形成R1中的半胱氨酸自由基，从而将异核中心降低到MN（III）/FE（III）状态。 Mn（III）/Fe（III）状态可以再生到Mn（IV）/Fe（III）状态进行进一步催化。 在先前的出版物中，我们（Younker等人）利用了CT R2的异核中心，并表征了MN（IV）/Fe（III）辅助因子的结构，利用了从MN和Fe侧和密度功能理论（DFT）计算的扩展X射线吸收细胞（EXAFS）。 现在，我们希望利用这些相同的技术在结构上表征MN（IV）/Fe（IV）中级。