The Biological and Chemical Function of Selenium in Enzymes

硒在酶中的生物和化学功能

基本信息

批准号：
8532933
负责人：
ROBERT J HONDAL
金额：
$ 30.6万
依托单位：
UNIVERSITY OF VERMONT & ST AGRIC COLLEGE
依托单位国家：
美国
项目类别：
财政年份：
2010
资助国家：
美国
起止时间：
2010-09-01 至 2015-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8532933
关键词：
Accounting Acidity Acids Active Sites Address Alzheimer&apos s Disease Amino Acids Antineoplastic Agents Apoptosis Apoptotic Back Biochemical Biochemical Reaction Biological Biological Process C-terminal C10 Cell Culture Techniques Cell Cycle Arrest Cell Proliferation Cell physiology Cells Chemicals Complex Cysteine Dissection Disulfides Dose Electron Transport Enzymes Epithelial Epithelial Cells Genetic Code Genome Goals Human Hydrogen Peroxide In Vitro Literature Lung Malignant Neoplasms Measures Mediating Methionine Methods Modeling Molecular Mus N-terminal Names Nature Neurodegenerative Disorders Nutritional Requirements Organism Oxidation-Reduction Oxidative Stress Oxygen Parents Parkinson Disease Pathogenesis Pathway interactions Play Process Property Proteins Reaction Reactive Oxygen Species Recovery Recycling Reduced Glutathione Relative (related person)Resistance Role Selenium Selenocysteine Sense Codon Speed Substrate Specificity Sulfhydryl Compounds Sulfinic Acids Sulfur System Terminator Codon Testing Thioredoxin Trace Elements Western Blotting antioxidant therapy base cancer cell chemical function chemical property cysteine sulfinic acid design dithiol enzyme mechanism human TXN protein in vivo methionine sulfoxide methionine sulfoxide reductase mutant oxidation pressure prevent public health relevance research study response selenoenzyme selenol therapeutic target thioredoxin reductase

项目摘要

DESCRIPTION (provided by applicant): Selenoenzymes use the rare amino acid selenocysteine, the so-called "21st" amino acid in the genetic code. Insertion of selenocysteine (Sec) into a protein is much more complicated than the other 20 amino acids because a UGA stop codon must be recoded as a sense codon for Sec and this process requires complex cellular machinery. Any explanation that accounts for the use of Sec in an enzyme must explain why it is needed relative to the use of the more commonly used cysteine (Cys) residue in order to justify maintaining the energetically costly Sec-insertion machinery. The most frequently given reasons for the use of Sec is that it is a type of "super-Cys" residue that can "speed reactions" due to selenium's superior chemical reactivity relative to sulfur. If this were true, then we might expect to find the use of Sec widely spread throughout nature instead of its observed rarity. We are pursuing a new hypothesis that explains the biological pressure to maintain the UGA recoding apparatus for Sec. This biological pressure is based upon the superior chemical property of selenium (relative to sulfur) to confer resistance to oxidation and we thus name it the "chemico-biological" rationale for the presence of Sec in enzymes. Sec can resist oxidation in two ways that Cys cannot. First when Sec is oxidized to seleninic acid (Sec-SeO2-) it can be converted back to the parent form (Sec-SeH) with relative ease compared to the extreme difficulty that the oxidized form of Cys (Cys-SO2-) can be converted to its parent form (Cys-SH). Second, it is much more difficult for Sec-SeO2- to be further oxidized to Sec-SeO3-, while Cys-SO2- can be oxidized to Cys-SO3- relatively easily. We believe both of these facts are unrecognized in the biochemical literature and our experiments will address the hypothesis that Sec only occurs in an enzyme when the enzyme needs to be very resistant to inactivation by oxidation. In other words Sec will substitute for Cys in an enzyme when this Cys-enzyme would otherwise be inactivated due to oxidation of its active-site Cys residue to sulfinic acid (Cys-SO2-). This major hypothesis will be addressed in this study by showing how the selenoenzymes thioredoxin reductase and methionine sulfoxide reductase resist oxidation using both in vitro and in vivo experiments. In the case of thioredoxin reductase we will show how the modular design of the enzyme is such that it carries within itself its own internal rescue system for reducing the Sec- SeO2- residue back to Sec-SeH. Thioredoxin reductase is a major therapeutic target for anti-cancer drugs due to its role in enhancing cell proliferation and regulating cellular apoptotic pathways. Oxidation of methionine to methionine sulfoxide is suspected to play a major role in neurodegenerative disorders such as Parkinson's and Alzheimer's diseases, and understanding how methionine sulfoxide reductase may become inactivated due to oxidation is critical to understanding how antioxidant therapies can best be used to prevent inactivation of the enzyme. The successful completion of the goals of this proposal will provide a universal chemical basis for the nutritional requirement of selenium in humans and other organisms. PUBLIC HEALTH RELEVANCE: Selenium is an essential trace element because it is required for incorporation into a specialized set of enzymes - selenoenzymes that use the rare amino acid selenocysteine. The primary selenoenzyme in this study, thioredoxin reductase is a major cancer target due to its role in preventing apoptosis (which cancer cells must avoid) and promoting cell proliferation. Cancer cells must divide rapidly to cause pathogenesis and require increased expression of thioredoxin reductase to survive.

描述（由申请人提供）：硒酶使用稀有的氨基酸硒代半胱氨酸，这是遗传密码中所谓的“ 21st”氨基酸。将硒代半胱氨酸（SEC）插入蛋白质比其他20个氨基酸更为复杂，因为UGA终止密码子必须作为SEC的感官密码子重新编码，并且此过程需要复杂的细胞机械。任何解释在酶中使用SEC的解释都必须解释为什么相对于使用更常用的半胱氨酸（CYS）残基需要它需要，以证明维持能量昂贵的SEC插入机械的合理性。使用SEC的最常见原因是，由于硒相对于硫相对于硫的优势化学反应性，它是一种可以“快速反应”的“超级cys”残基。如果这是真的，那么我们可能会期望发现SEC的使用在整个自然界中广泛传播，而不是其观察到的稀有性。我们正在追求一个新的假设，该假设解释了维持SEC的UGA重新编码设备的生物压力。这种生物压力基于硒（相对于硫）的优质化学特性，以赋予氧化的耐药性，因此我们将其称为“化学生物生物学”基本原理，用于在酶中存在SEC。 SEC可以通过两种方式抵抗CYS不能的氧化。首先，当SEC被氧化为硒酸（SEC-SEO2-）时，与极端难度相比，可以将CYS（CYS-SO2-）的极端难度转换为母体形式（SEC-SEH），可以将其转换回父型（sec-seh）。其次，Sec-Seo2-更难将其进一步氧化为Sec-Seo3-，而CYS-SO2-可以相对容易氧化为Cys-SO3-相对容易。我们认为，这两个事实在生化文献中都无法识别，我们的实验将解决以下假设：SEC仅在酶需要非常耐氧化而被氧化时发生。换句话说，由于其活性位点Cys残基与硫酸酸（Cys-SO2-）氧化，因此SEC将在酶中代替酶中的Cys。这项研究将在本研究中解决这一主要假设，以说明如何使用体外和体内实验均如何使用体外和体内实验来抗氧化蛋白还原酶和甲二氨酸磺氧化氧化物还原酶抵抗氧化。在硫氧还蛋白还原酶的情况下，我们将如何展示该酶的模块化设计如何在其内部自身携带其自身的内部救援系统，以将SEC-SEO2残留物减少到SEC-SEH。硫氧还蛋白还原酶是抗癌药物的主要治疗靶标，因为它在增强细胞增殖和调节细胞凋亡途径中的作用。怀疑将蛋氨酸氧化为甲氨酸硫氧化物，在神经退行性疾病中起主要作用，例如帕金森氏症和阿尔茨海默氏症的疾病，了解蛋氨酸磺代还原酶还原酶可能如何因氧化而灭活蛋氨酸硫氨酸的疾病，这对于理解抗氧化治疗的方法是对抗氧化治疗的最佳使用，可以最好地使用抗氧化治疗。该提案的目标成功完成将为人类和其他生物中硒的营养需求提供普遍的化学基础。公共卫生相关性：硒是必不可少的痕量元素，因为它是将使用稀有氨基酸硒代半胱氨酸的专业酶（硒酶）掺入的。硫氧还蛋白还原酶在这项研究中的主要硒酶是主要的癌症靶标，因为它在预防凋亡（必须避免哪些癌细胞）和促进细胞增殖中的作用。癌细胞必须迅速分裂以引起发病机理，并需要增加硫氧还蛋白还原酶的表达才能生存。

项目成果

期刊论文数量（11）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

A direct and continuous assay for the determination of thioredoxin reductase activity in cell lysates.

DOI：
10.1016/j.ab.2013.08.013
发表时间：
2013-12-01
期刊：
Analytical biochemistry
影响因子：
2.9
作者：
Cunniff B;Snider GW;Fredette N;Hondal RJ;Heintz NH
通讯作者：
Heintz NH

Comparison of the redox chemistry of sulfur- and selenium-containing analogs of uracil.

尿嘧啶的含硫和含硒类似物的氧化还原化学的比较。

DOI：
10.1016/j.freeradbiomed.2017.01.028
发表时间：
2017-03
期刊：
Free radical biology & medicine
影响因子：
7.4
作者：
Payne NC;Geissler A;Button A;Sasuclark AR;Schroll AL;Ruggles EL;Gladyshev VN;Hondal RJ
通讯作者：
Hondal RJ

Selenium as an electron acceptor during the catalytic mechanism of thioredoxin reductase.

DOI：
10.1021/bi400658g
发表时间：
2014-02-04
期刊：
BIOCHEMISTRY
影响因子：
2.9
作者：
Lothrop, Adam P.;Snider, Greg W.;Ruggles, Erik L.;Patel, Amar S.;Lees, Watson J.;Hondal, Robert J.
通讯作者：
Hondal, Robert J.

Resolution of oxidative stress by thioredoxin reductase: Cysteine versus selenocysteine.

DOI：
10.1016/j.redox.2014.01.021
发表时间：
2014
期刊：
Redox biology
影响因子：
11.4
作者：
Cunniff B;Snider GW;Fredette N;Stumpff J;Hondal RJ;Heintz NH
通讯作者：
Heintz NH

Reduction of cysteine-S-protecting groups by triisopropylsilane.

DOI：
10.1002/psc.3130
发表时间：
2018-11
期刊：
Journal of peptide science : an official publication of the European Peptide Society
影响因子：
0
作者：
Ste Marie EJ;Hondal RJ
通讯作者：
Hondal RJ