Kinetic consequences of the endogenous ligand to molybdenum in the DMSO reductase family: a case study with periplasmic nitrate reductase
Kinetic consequences of the endogenous ligand to molybdenum in the DMSO reductase family: a case study with periplasmic nitrate reductase
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DOI：
10.1007/s00775-020-01833-9
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发表时间：
2020-11
期刊：
影响因子：
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通讯作者：
Breeanna Mintmier;Jennifer M. McGarry;D. Bain;P. Basu
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文献类型：
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作者：
Breeanna Mintmier;Jennifer M. McGarry;D. Bain;P. Basu
蝶呤酶家族催化多种底物，在碳、氮、砷和硒的循环中起着关键作用。二甲基亚砜还原酶（DMSOR）亚家族是最多样化的异蝶呤酶家族，并且该家族的成员催化微生物生命过程中重要的无数反应。DMSOR家族中的酶可以转化多种底物;然而，关于底物偏好的定量信息很少，更重要的是，底物选择性的原因尚不清楚。钼配位长期以来一直被认为会影响酶的催化活性。具体地，氘配位残基可以调节底物偏好。因此，利用多蝶呤酶周质硝酸还原酶（Nap）作为媒介物来理解底物偏好并描绘通过交换钼配体施加的差异的动力学基础。为此，已异源过表达来自空肠弯曲杆菌的NapA，并产生了一系列变体，其中钼配位半胱氨酸已被另一种氨基酸取代。讨论了这些变体的动力学特性，并与天然酶的动力学特性进行了比较，为理解氘配位残基的功能提供了定量信息。
AbstractThe molybdopterin enzyme family catalyzes a variety of substrates and plays a critical role in the cycling of carbon, nitrogen, arsenic, and selenium. The dimethyl sulfoxide reductase (DMSOR) subfamily is the most diverse family of molybdopterin enzymes and the members of this family catalyze a myriad of reactions that are important in microbial life processes. Enzymes in the DMSOR family can transform multiple substrates; however, quantitative information about the substrate preference is sparse, and, more importantly, the reasons for the substrate selectivity are not clear. Molybdenum coordination has long been proposed to impact the catalytic activity of the enzyme. Specifically, the molybdenum-coordinating residue may tune substrate preference. As such, molybdopterin enzyme periplasmic nitrate reductase (Nap) is utilized as a vehicle to understand the substrate preference and delineate the kinetic underpinning of the differences imposed by exchanging the molybdenum ligands. To this end, NapA fromCampylobacter jejunihas been heterologously overexpressed, and a series of variants, where the molybdenum coordinating cysteine has been replaced with another amino acid, has been produced. The kinetic properties of these variants are discussed and compared with those of the native enzyme, providing quantitative information to understand the function of the molybdenum-coordinating residue.Graphic abstract