n nnnThe molybdenum cofactor (Moco) is a prosthetic group requiredby a number of enzymes, such as nitrate reductase, sulfite oxidase,xanthine dehydrogenase, and aldehyde oxidase. Its biosynthesisin eukaryotes can be divided into four steps, of which the lastthree are proposed to occur in the cytosol. Here, we reportthat the mitochondrial ABC transporter ATM3, previously implicatedin the maturation of extramitochondrial iron-sulfur proteins,has a crucial role also in Moco biosynthesis. In ATM3 insertionmutants of Arabidopsis thaliana, the activities of nitrate reductaseand sulfite oxidase were decreased to 50%, whereas the activitiesof xanthine dehydrogenase and aldehyde oxidase, whose activitiesalso depend on iron-sulfur clusters, were virtually undetectable.Moreover, atm3 mutants accumulated cyclic pyranopterin monophosphate,the first intermediate of Moco biosynthesis, but showed decreasedamounts of Moco. Specific antibodies against the Moco biosynthesisproteins CNX2 and CNX3 showed that the first step of Moco biosynthesisis localized in the mitochondrial matrix. Together with theobservation that cyclic pyranopterin monophosphate accumulatedin purified mitochondria, particularly in atm3 mutants, ourdata suggest that mitochondria and the ABC transporter ATM3have a novel role in the biosynthesis of Moco.展开▼
机译:ABSTRACTn FONT> TH> TR> TABLE> n
n TOP n <字体颜色= 464c53>抽象 FONT> n 介绍 n 结果 n 讨论 n 方法 n 参考文献 n FONT> TH> TR> TABLE> n nnn钼辅因子(Moco)是 sup>酶的种类很多,例如硝酸还原酶,亚硫酸氧化酶, SUP>黄嘌呤脱氢酶和醛氧化酶。它在真核生物中的生物合成 SUP>可以分为四个步骤,其中最后三个 SUP>被提议在细胞质中发生。在这里,我们报道 SUP>,先前与 SUP>有关的线粒体ABC转运蛋白ATM3在线粒体铁硫蛋白的成熟中也起着至关重要的作用。 Moco生物合成。在拟南芥 I>的 ATM3 I>插入 SUP>突变体中,硝酸还原酶 SUP>和亚硫酸盐氧化酶的活性降低至 50%,而黄嘌呤脱氢酶和醛氧化酶的活性 SUP>也具有活性 SUP> SUP>此外, atm3 I>突变体积累了环吡喃蝶呤单磷酸, SUP> Moco生物合成的第一个中间体,但显示出 SUP>的Moco数量减少了。针对Moco生物合成 SUP>蛋白CNX2和CNX3的特异性抗体表明,Moco生物合成 SUP>的第一步位于线粒体基质中。结合 SUP>观察,环吡喃蝶呤单磷酸在纯化的线粒体中,尤其是在 atm3 I>突变体中积累了 SUP>,我们的 SUP>数据表明线粒体和ABC转运蛋白ATM3 SUP>在Moco的生物合成中具有新作用。 SUP>
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