Structure/Function Relationships in Cysteine and Cysteamine Dioxygenases

半胱氨酸和半胱胺双加氧酶的结构/功能关系

• 批准号: 9330899
• 负责人: Thomas Christian Brunold
• 金额: $ 27.14万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2020-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9330899
• 关键词: Acids; Active Sites; Address; Alzheimer' s Disease; Amino Acids; Anabolism; Arginine; Autoimmune Diseases; Binding; Biochemical; Biological; Brain; Cardiac; Catalysis; Coenzyme A; Collaborations; Comparative Study; Complex; Crystallization; Crystallography; Cysteamine; Cysteine; Cysteine dioxygenase; Cystine; Cystinuria; Data; Decarboxylation; Development; Dioxygenases; Disease; Disulfides; Duodenum; Effectiveness; Electrons; Environment; Enzyme Kinetics; Enzymes; Excretory function; Exhibits; Face; Generations; Glutamine; Glutathione; Glycine; Goals; Growth; Human; Hydrogen Peroxide; Inorganic Chemistry; Inorganic Sulfates; Ischemia; Kidney; Lead; Ligands; Link; Mammals; Membrane; Methodology; Mind; Modeling; Molecular; Molecular Biology; Motor Neuron Disease; Nature; Neurodegenerative Disorders; Neurons; Neurotransmitters; Organism; Oxides; Parkinson Disease; Pathway interactions; Play; Positioning Attribute; Process; Production; Proteins; Rattus; Reaction; Research; Rest; Role; Skeletal Muscle; Specificity; Structure; Structure-Activity Relationship; Substrate Interaction; Substrate Specificity; Sulfhydryl Compounds; Sulfur; Taurine; Teratogens; Testing; Tissues; Triad Acrylic Resin; Tyrosine; Variant; adduct; analog; carboxylate; computerized tools; cross reactivity; crosslink; cysteine sulfinic acid; developmental disease; electronic structure; enzyme mechanism; excitotoxicity; hypotaurine; in vivo; insight; nervous system disorder; oxidation; scaffold; semi essential amino acid; small molecule; three dimensional structure

Project Summary L-Cysteine (Cys) is an essential building block for the biosynthesis of new proteins and serves as a precursor for several biologically important sulfur-containing molecules, such as coenzyme A, taurine, glutathione, and inorganic sulfate. However, organisms must tightly regulate the concentration of exogenous Cys, as elevated levels of this semi-essential amino acid can be extremely harmful. The non- heme iron enzyme cysteine dioxygenase (CDO) serves to maintain the proper Cys levels by catalyzing the oxidation of Cys to cysteine sulfinic acid. Malfunctioning of CDO and the consequent accumulation of Cys have been linked to several neurodegenerative diseases. The decarboxylation of Cys during coenzyme A synthesis generates cysteamine. The constitutive degradation of coenzyme A releases this cysteamine moiety, which can be converted to hypotaurine by the non-heme iron enzyme cysteamine (2-aminoethanethiol) dioxygenase (ADO). Hypotaurine is subsequently oxidized to taurine, an amino thiol acid that plays numerous important roles in mammalian tissues, including maintaining cardiac functions, protecting neural cells from excitotoxicity and ischemia, serving as a neurotransmitter, and stabilizing skeletal muscle membrane. Despite catalyzing the oxidation of two structurally similar thiol compounds, CDO and ADO show very inefficient cross-utilization of substrates. By studying CDO and ADO in parallel, we are presented with an opportunity to conclusively determine the substrate selectivity mechanism each enzyme employs, and thus how Cys and cysteamine levels may be independently regulated in vivo. The overall objective of the research outlined in this proposal is, therefore, to identify the roles of key amino acid residues with regards to substrate selectivity, positioning, and activation in the CDO and ADO catalytic mechanisms. With this objective in mind, we have devised the following Specific Aims: 1. Elucidate structure/function relationships in the catalytic mechanism of CDO. 2. Assess the effects of differences in key conserved amino acid residues between eukaryotic and prokaryotic CDOs on the nature of active site/substrate interactions. 3. Establish the order and modes by which the substrates cysteamine and O2 bind to the ADO active site and the mechanism of thiol oxidation. 4. Explore the geometric/electronic structures and reaction mechanisms of CDO and ADO mimics. To accomplish these aims, we will employ a combination of biochemical, spectroscopic, and computational tools for studying the resting states and substrate (analogue) adducts of the native enzymes, select variants, and small-molecule functional CDO and ADO mimics.

项目摘要 l-晶体半胱氨酸（CYS）是新蛋白质生物合成的重要组成部分，并用作 几种具有生物学上重要的含硫分子的前体，例如辅酶A，牛磺酸， 谷胱甘肽和无机硫酸盐。但是，生物必须严格调节 外源性CYS，因为这种半必需氨基酸的水平升高可能非常有害。非 - 血红素铁酶半胱氨酸二氧酶（CDO）通过催化来维持适当的CYS水平 CYS氧化为半胱氨酸硫酸硫酸。 CDO故障和随之而来的CYS积累 与几种神经退行性疾病有关。 辅酶A合成过程中Cys的脱羧会产生cysteamine。本构 辅酶A的降解释放了这个cysteamine部分，可以通过 非血红素铁酶Cysteamine（2-氨乙二醇）二氧酶（ADO）。低位是 随后氧化为牛磺酸，牛磺酸是一种在哺乳动物中起许多重要作用的氨基硫醇 组织，包括维持心脏功能，保护神经细胞免受兴奋性毒性和缺血性， 用作神经递质，并稳定骨骼肌膜。 尽管催化了两种结构相似的硫醇化合物的氧化，但CDO和ADO非常显示 底物的效率低下。通过并联研究CDO和ADO，我们将为我们提供 最终确定每个酶采用的底物选择性机制的机会，从而 Cys和Cysteamine水平如何在体内独立调节。总体目标 因此，该提案中概述的研究是确定关键氨基酸残基的作用 在CDO和ADO催化机制中的底物选择性，定位和激活。 考虑到这个目标，我们已经设计了以下特定目标： 1。阐明CDO催化机理中的结构/功能关系。 2。评估真核和 主活性位点/底物相互作用的性质的实质性CDO。 3。建立底物cysteamine和O2结合到ADO活性位点的顺序和模式 以及硫醇氧化的机制。 4。探索CDO和ADO模拟的几何/电子结构和反应机制。 为了实现这些目标，我们将采用生化，光谱和计算的组合 研究天然酶的静止状态和底物（类似）加合物的工具，选择 变体以及小分子的功能CDO和ADO模拟。