Structure of an aromatic-ring-hydroxylating dioxygenase-naphthalene 1,2-dioxygenase
Structure of an aromatic-ring-hydroxylating dioxygenase-naphthalene 1,2-dioxygenase
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DOI：
10.1016/s0969-2126(98)00059-8
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发表时间：
1998-05-15
期刊：
影响因子：
5.7
通讯作者：
Ramaswamy, S
中科院分区：
文献类型：
--
作者：
Kauppi, B;Lee, K;Ramaswamy, S
背景：假单胞菌属。 NCIB 9816-4 利用多组分酶系统将萘氧化为 (+)-顺式-(1R,PS)-二羟基-1,2-二氢萘。催化该反应的酶成分萘 1,2-双加氧酶 (NDO) 属于芳环羟基化双加氧酶家族，可将芳香烃和相关化合物氧化为顺式芳烃二醇。这些酶利用单核非血红素铁中心催化将分子氧添加到各自的底物上。本研究的目的是提供阐明 NDO 作用机制所需的基本结构信息。结果：NDO 的三维结构已在 2.25 埃分辨率下确定。该分子是α(3)β(3)六聚体。 α 亚基具有一个包含 Rieske [2Fe-2S] 中心的 β 片层结构域和一个催化结构域，该催化结构域具有由螺旋堆积的反平行九链 β 折叠片主导的新型折叠。活性位点包含由 His208、His213、Asp362（双齿）和水分子配位的非血红素亚铁离子。 Asn201 的位置较远，为 3.75 埃，位于八面体缺失的轴向位置。在 Rieske [2Fe-2S] 中心，一个铁由 Cys81 和 Cys101 配位，另一个由 His83 和 His104 配位。结论：Rieske 结构域的结构域和铁配位与细胞色素 bc(1) 结构域非常相似。其中一个 α 亚基的活性位点铁中心通过单个氨基酸 Asp205 通过氢键直接连接到相邻 ex 亚基中的 Rieske [2Fe-2S] 中心。这可能是电子转移的主要途径。
Background: Pseudomonas sp. NCIB 9816-4 utilizes a multicomponent enzyme system to oxidize naphthalene to (+)-cis-(1R,PS)-dihydroxy-1,2-dihydronaphthalene. The enzyme component catalyzing this reaction, naphthalene 1,2-dioxygenase (NDO), belongs to a family of aromatic-ring-hydroxylating dioxygenases that oxidize aromatic hydrocarbons and related compounds to cis-arene diols. These enzymes utilize a mononuclear non-heme iron center to catalyze the addition of dioxygen to their respective substrates. The present study was conducted to provide essential structural information necessary for elucidating the mechanism of action of NDO.Results: The three-dimensional structure of NDO has been determined at 2.25 Angstrom resolution. The molecule is an alpha(3) beta(3) hexamer. The alpha subunit has a beta-sheet domain that contains a Rieske [2Fe-2S] center and a catalytic domain that has a novel fold dominated by an antiparallel nine-stranded beta-pleated sheet against which helices pack. The active site contains a non-heme ferrous ion coordinated by His208, His213, Asp362 (bidentate) and a water molecule. Asn201 is positioned further away, 3.75 Angstrom, at the missing axial position of an octahedron, In the Rieske [2Fe-2S] center, one iron is coordinated by Cys81 and Cys101 and the other by His83 and His104.Conclusions: The domain structure and iron coordination of the Rieske domain is very similar to that of the cytochrome bc(1) domain. The active-site iron center of one of the alpha subunits is directly connected by hydrogen bonds through a single amino acid, Asp205, to the Rieske [2Fe-2S] center in a neighboring ex subunit. This is likely to be the main route for electron transfer.