LONG RANGE RADICAL INITIATION IN E COLI RIBONUCLEOTIDE REDUCTASE

大肠杆菌核糖核苷酸还原酶中的长程自由基引发

• 批准号: 7723929
• 负责人: JOANNE STUBBE
• 金额: $ 0.1万
• 依托单位: CORNELL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-01 至 2009-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7723929
• 关键词: Binding; Binding Sites; Catalysis; Complex; Computer Retrieval of Information on Scientific Projects Database; Cysteine; Diphosphates; Docking; Electron Transport; Funding; Grant; Housing; Institution; Iron; Measurement; Modeling; Nucleotides; Pathway interactions; Process; Proteins; Range; Rate; Research; Research Personnel; Resources; Ribonucleotide Reductase; Source; Structure; Substrate Specificity; Thinking; United States National Institutes of Health; cofactor; nucleoside diphosphate

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. E.coli ribonucleotide reductase catalyzes the conversion of nucleoside diphosphates (NDP) to deoxynucleoside diphosphates. The active protein is composed of two homodimeric subunits (R1 and R2) thought to form a 1:1 complex. R1 binds the NDP substrates, houses the essential cysteines required for catalysis and the binding sites for the allosteric effectors that govern substrate specificity and turnover rates. R2 harbors the essential di-iron tyrosyl radical cofactor on residue 122 (Y?). A major unresolved issue is the mechanism of radical initiation: how the tyrosyl radical (Y?) in R2 generates a transient thiyl radical (C439?) in R1 required for nucleotide reduction. The current model for the radical initiation process involves a specific electron transfer pathway, which traverses a distance of 3.5 nm, derived from a docking model of the R1 and R2 structures, but a substantial part of the pathway is not apparent from the available structural information. A measurement of the distance between Y122 and C439 was imperative to establish the radical initiation model.

该子项目是利用该技术的众多研究子项目之一 资源由 NIH/NCRR 资助的中心拨款提供。子项目及 研究者 (PI) 可能已从 NIH 的另一个来源获得主要资金， 因此可以在其他 CRISP 条目中表示。列出的机构是 对于中心来说，它不一定是研究者的机构。 大肠杆菌核糖核苷酸还原酶催化核苷二磷酸 (NDP) 转化为脱氧核苷二磷酸。该活性蛋白由两个同源二聚体亚基（R1 和 R2）组成，被认为形成 1:1 复合物。 R1 结合 NDP 底物，包含催化所需的必需半胱氨酸以及控制底物特异性和周转率的变构效应子的结合位点。 R2 在残基 122 (Y?) 上含有必需的二铁酪氨酰基辅因子。一个未解决的主要问题是自由基引发的机制：R2 中的酪氨酰基（Y？）如何在 R1 中产生核苷酸还原所需的瞬时硫基自由基（C439？）。目前的自由基引发过程模型涉及特定的电子转移途径，该途径的距离为 3.5 nm，源自 R1 和 R2 结构的对接模型，但从现有的结构信息来看，该途径的很大一部分并不明显。测量 Y122 和 C439 之间的距离对于建立自由基引发模型至关重要。