Diiron monooxygenases in natural product biosynthesis.
Diiron monooxygenases in natural product biosynthesis.
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DOI：
10.1039/c7np00061h
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发表时间：
2018-07-18
影响因子：
11.9
通讯作者：
Lipscomb JD
中科院分区：
文献类型：
--
作者：
Komor AJ;Jasniewski AJ;Que L;Lipscomb JD
非血红素双核铁簇单加氧酶在天然产物生物合成途径中的作用直到最近才被认识到。目前，已发现两个家族。第一个家族的原型成员CmlA催化L-对氨基苯丙氨酸(L-PAPA)与非核糖体多肽合成酶CmlP共价连接的β-羟基化，从而影响了维尼链霉菌生物合成氯霉素的第一步。CmlA在金属β-内酰胺酶蛋白折叠中包含二铁簇，而不是几乎所有其他二铁单加氧酶的4螺旋束折叠。CmlA通过L-PapA负载的CmlP：CmlA复合体的形成而引起的结构变化，将O2激活和底物羟化偶联。另一个新的双铁家族以AurF和CmlI两种酶为代表，它们催化芳胺底物与O2结合生成芳基硝基产物。硫代链霉菌的AurF催化对氨基苯甲酸生成对硝基苯甲酸酯，作为生物活性化合物金黄色的前体，而来自金黄色链霉菌的CmlI催化氯霉素生物合成的最终芳胺到芳基硝基步骤。这两种酶都稳定了一种新型的过氧中间体作为活性物种。CmlI和AurF罕见的6电子N氧化反应涉及两个递进氧化途径的中间体。这些酶通过利用其中一个反应途径中间体作为双铁簇的原位还原剂来优化效率，同时生成下一个途径中间体。对于CmlI，这种还原允许完成生物合成所需的过氧基中间体的中途再生。CmlI通过在不分离中间产物的情况下进行多步芳胺氧化来确保特异性。两个新的含二铁簇的加氧酶家族作为NRPS和PKS生物合成系统的剪裁酶。
The participation of non-heme dinuclear iron cluster-containing monooxygenases in natural product biosynthetic pathways has been recognized only recently. At present, two families have been discovered. The archetypal member of the first family, CmlA, catalyzes β-hydroxylation of L-p-aminophenylalanine (L-PAPA) covalently linked to the nonribosomal peptide synthetase (NRPS) CmlP, thereby effecting the first step in the biosynthesis of chloramphenicol by Streptomyces venezuelae. CmlA houses the diiron cluster in a metallo-β-lactamase protein fold instead of the 4-helix bundle fold of nearly every other diiron monooxygenase. CmlA couples O2 activation and substrate hydroxylation via a structural change caused by formation of the L-PAPA-loaded CmlP:CmlA complex. The other new diiron family is typified by two enzymes, AurF and CmlI, which catalyze conversion of aryl-amine substrates to aryl-nitro products with incorporation of oxygen from O2. AurF from Streptomyces thioluteus catalyzes the formation of p-nitrobenzoate from p-aminobenzoate as a precursor to the biostatic compound aureothin, whereas CmlI from S. venezuelae catalyzes the ultimate aryl-amine to aryl-nitro step in chloramphenicol biosynthesis. Both enzymes stabilize a novel type of peroxo-intermediate as the reactive species. The rare 6-electron N-oxygenation reactions of CmlI and AurF involve two progressively oxidized pathway intermediates. The enzymes optimize efficiency by utilizing one of the reaction pathway intermediates as an in situ reductant for the diiron cluster, while simultaneously generating the next pathway intermediate. For CmlI, this reduction allows mid-pathway regeneration of the peroxo intermediate required to complete the biosynthesis. CmlI ensures specificity by carrying out the multistep aryl-amine oxygenation without dissociating intermediate products. Two new families of diiron cluster-containing oxygenases serve as tailoring enzymes for NRPS and PKS biosynthetic systems.