The Fe(II)/α-ketoglutarate-dependent taurine dioxygenases from Pseudomonas putida and Escherichia coli are tetramers
The Fe(II)/α-ketoglutarate-dependent taurine dioxygenases from Pseudomonas putida and Escherichia coli are tetramers
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DOI：
10.1111/j.1742-4658.2012.08473.x
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发表时间：
2012-03-01
期刊：
影响因子：
5.4
通讯作者：
Dobbek, Holger
中科院分区：
文献类型：
--
作者：
Knauer, Stefan H.;Hartl-Spiegelhauer, Olivia;Dobbek, Holger
Fe（II）/α-酮戊二酸依赖性加氧酶是与许多不同生物功能相关的通用催化剂，其中它们使用活化的双氧的氧化能力来转化各种底物。单核非血红素铁中心用于将辅底物α-酮戊二酸的脱羧与底物的双电子氧化偶联，这在大多数情况下是羟基化。虽然Fe（II）/α-酮戊二酸依赖性加氧酶具有不同的氨基酸序列和底物特异性，但假定它们具有共同的机制。该酶家族的一个代表是Fe（II）/α-酮戊二酸依赖性牛磺酸双加氧酶，其催化牛磺酸的羟基化，产生亚硫酸盐和氨基乙醛。它的作用机制已被详细研究，成为整个酶家族的模型系统。然而，它的低聚状态和结构一直有争议。在这里，我们报告的Fe（II）/α-酮戊二酸依赖性牛磺酸双加氧酶恶臭假单胞菌KT 2440（TauDPp）的生化和动力学特性。我们还提出了这种酶的载脂蛋白形式的三种晶体结构。与牛磺酸双加氧酶从大肠杆菌（TauDEc）的比较表明，这两种酶是非常相似的关于他们的光谱，结构和动力学，只有微小的差异，在反应过程中的中间体的积累已被观察到。结构数据和分析凝胶过滤，以及沉降速度分析超离心，表明TauDPp和TauDEc在溶液和晶体中都是四聚体，这与早期描述的来自E.大肠杆菌作为二聚体。
Fe(II)/a-ketoglutarate-dependent oxygenases are versatile catalysts associated with a number of different biological functions in which they use the oxidizing power of activated dioxygen to convert a variety of substrates. A mononuclear nonheme iron center is used to couple the decarboxylation of the cosubstrate a-ketoglutarate with a two-electron oxidation of the substrate, which is a hydroxylation in most cases. Although Fe(II)/a-ketoglutarate-dependent oxygenases have diverse amino acid sequences and substrate specifity, it is assumed that they share a common mechanism. One representative of this enzyme family is the Fe(II)/a-ketoglutarate-dependent taurine dioxygenase that catalyzes the hydroxylation of taurine yielding sulfite and aminoacetaldehyde. Its mechanism has been studied in detail becoming a model system for the whole enzyme family. However, its oligomeric state and architecture have been disputed. Here, we report the biochemical and kinetic characterization of the Fe(II)/a-ketoglutarate-dependent taurine dioxygenase from Pseudomonas putida KT2440 (TauDPp). We also present three crystal structures of the apo form of this enzyme. Comparisons with taurine dioxygenase from Escherichia coli (TauDEc) demonstrate that both enzymes are quite similar regarding their spectra, structure and kinetics, and only minor differences for the accumulation of intermediates during the reaction have been observed. Structural data and analytical gel filtration, as well as sedimentation velocity analytical ultracentrifugation, show that both TauDPp and TauDEc are tetramers in solution and in the crystals, which is in contrast to the earlier description of taurine dioxygenase from E. coli as a dimer.