MOLYBDENUM COFACTOR--BIOSYNTHESIS AND FUNCTION

钼辅因子--生物合成和功能

• 批准号: 6350716
• 负责人: HERMANN SCHINDELIN
• 金额: $ 16.46万
• 依托单位: STATE UNIVERSITY NEW YORK STONY BROOK
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-03-01 至 2003-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6350716
• 关键词: X ray crystallography; biosynthesis; biotin; chemical structure function; cofactor; dimethylsulfoxide; enzyme activity; lyase; molybdenum; nutrition related tag; oxidoreductase; oxidoreductase inhibitor; pteridines; site directed mutagenesis; sulfoxide; tissue /cell culture

The molybdenum cofactor (Moco) is present in four different enzyme families which catalyze important transformations in the global carbon, sulfur and nitrogen cycles. Moco consists of a mononuclear molybdenum coordinated to the sulfur atoms of a dithiolene group which is part of a substituted pterin derivative termed molybdopterin. Enzymes containing this cofactor are found in all three phylogenetic kingdoms of life, and biosynthesis of the cofactor follows the same pathway, both in prokaryotes and in eukaryotes including plants and human. Moco deficiency is inherited as an autosomal recessive trait and is a severe disease in humans which manifests itself in neurological abnormalities leading to premature death in the affected individuals. The experiments outlined in this proposal address two important aspects of Moco, namely its biosynthesis and its detailed function once it has been incorporated into the target enzymes. The specific aims presented in this proposal therefore are: (i) Characterization of the early steps in Moco biosynthesis through structural studies on the enzyme MoaC. MoaC most likely either catalyzes the first step in Moco biosynthesis starting with a phosphorylated guanosine, or the second step in which A molybdopterin precursor is generated which still lacks the sulfur atoms. (ii) Crystal structure analysis of molybdopterin synthase which incorporates the sulfur atoms into a molybdopterin precursor generating molybdopterin. The small subunit of the heterodimeric molybdopterin synthase contains an unusual C-terminal thiocarboxylate which serves as the sulfur donor during catalysis. (iii) Crystal structure determination of MogA which might function as a molybdochelatase and thus would be responsible for incorporating molybdenum, which is present in the cell as molybdate, into the molybdopterin. (iv) High resolution structure analysis of the Moco-containing enzyme dimethylsulfoxide reductase including characterization of different oxidation states and complexes of the enzyme with substrates and inhibitors which will lead to a detailed characterization of the catalytic mechanism. (v) Crystal structure analysis of biotin sulfoxide reductase, which is related in sequence to dimethylsulfoxide reductase but differs in substrate specificity. Comparative studies of the two enzymes will lead to a more general understanding of the roles Moco is playing in enzymes containing this cofactor.

钼辅助因子(MOCO)存在于四种不同的酶中 这些家族催化了全球碳的重要转变， 硫磺和氮气循环。MoCO由单核钼组成 配位到二硫烯基的硫原子，该二硫烯基是 一种被称为钼多蝶呤的取代的蝶呤衍生物。酶类 在所有三个系统发育的王国中都发现了含有这种辅因子的 和辅因子的生物合成遵循相同的途径，两者 在原核生物和真核生物中，包括植物和人类。MOCO 缺乏症是一种常染色体隐性遗传，是一种严重的 人类的一种疾病，表现为神经异常 导致受影响的个人过早死亡。这些实验 本提案中概述了MOCO的两个重要方面，即 它的生物合成及其一旦被结合后的详细功能 转化为目标酶。这项提案提出的具体目标 因此是：(I)描述MOCO早期步骤的特征 通过对MoaC酶的结构研究进行生物合成。MoaC MOST 很可能是催化了Moco生物合成的第一步 用磷酸化的鸟苷，或者第二步A 生成了仍然缺乏硫原子的钼掺杂前驱体。 (Ii)钼杂喋素合成酶的晶体结构分析 将硫原子合并到钼掺杂蝶呤前体生成中 钼倍半乳剂。杂二聚体钼掺杂的小亚基 合成酶含有一种不寻常的C-末端硫代羧酸盐，它的作用是 催化过程中的硫供体。(三)晶体结构 可能具有钼螯合酶功能的MOGA的测定和 因此，将负责结合钼，这是存在的 在细胞中以钼酸盐的形式，进入钼的掺杂物。(四)高分辨率 含钼酶二甲基亚砜的结构分析 还原酶包括不同氧化态的特性和 该酶与底物和抑制剂的络合物将导致 对催化机理进行了详细表征。(V)水晶 生物素亚砜还原酶的结构分析 与二甲基亚砜还原酶序列不同但底物不同 专一性。对这两种酶的比较研究将导致更多 对MOCO在含有以下物质的酶中所起作用的一般了解 这个辅因。