Structural and biochemical identification of a novel bacterial oxidoreductase
Structural and biochemical identification of a novel bacterial oxidoreductase
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DOI：
10.1074/jbc.m408876200
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发表时间：
2004-11-26
影响因子：
4.8
通讯作者：
Strynadka, NCJ
中科院分区：
文献类型：
--
作者：
Loschi, L;Brokx, SJ;Strynadka, NCJ
通过使用大肠杆菌基因组的生物信息学筛选潜在的含腺嘌呤的酶，我们已经确定了一种新的氧化还原酶保守的大多数革兰氏阴性菌。所确定的操纵子编码一个建议的异二聚体，YedYZ在大肠杆菌中，由一个可溶性催化亚基，称为YedY，这可能是锚定到膜的血红素含有跨膜亚基，称为YedZ。YedY的独特特征在于存在一个未与额外核苷酸缀合的钼蝶呤，并且它代表了从E.以存在这种辅因子形式为特征的大肠杆菌。我们已经通过使用晶体学分析进一步表征了钼和钨取代形式的催化亚基YedY。YedY在整体结构上与所有已知的细菌还原酶非常不同，但确实显示出与真核鸡肝亚硫酸盐氧化酶的催化结构域的一些相似性。然而，严格保守的残基参与的金属配位领域和YedY的底物结合口袋是惊人的不同，从鸡肝亚硫酸盐氧化酶，这表明催化活性更符合还原酶比亚硫酸盐氧化酶。初步动力学分析的YedY与各种基板支持我们的建议，YedY和它的许多直系同源物可能代表一种新型的膜相关的细菌还原酶。
By using a bioinformatics screen of the Escherichia coli genome for potential molybdenum-containing enzymes, we have identified a novel oxidoreductase conserved in the majority of Gram-negative bacteria. The identified operon encodes for a proposed heterodimer, YedYZ in Escherichia coli, consisting of a soluble catalytic subunit termed YedY, which is likely anchored to the membrane by a heme-containing trans-membrane subunit termed YedZ. YedY is uniquely characterized by the presence of one molybdenum molybdopterin not conjugated by an additional nucleotide, and it represents the only molybdoenzyme isolated from E. coli characterized by the presence of this cofactor form. We have further characterized the catalytic subunit YedY in both the molybdenum- and tungsten-substituted forms by using crystallographic analysis. YedY is very distinct in overall architecture from all known bacterial reductases but does show some similarity with the catalytic domain of the eukaryotic chicken liver sulfite oxidase. However, the strictly conserved residues involved in the metal coordination sphere and in the substrate binding pocket of YedY are strikingly different from that of chicken liver sulfite oxidase, suggesting a catalytic activity more in keeping with a reductase than that of a sulfite oxidase. Preliminary kinetic analysis of YedY with a variety of substrates supports our proposal that YedY and its many orthologues may represent a new type of membrane-associated bacterial reductase.