Specific Interactions between the Ferredoxin and Terminal Oxygenase Components of a Class IIB Rieske Nonheme Iron Oxygenase, Carbazole 1,9a-Dioxygenase
Specific Interactions between the Ferredoxin and Terminal Oxygenase Components of a Class IIB Rieske Nonheme Iron Oxygenase, Carbazole 1,9a-Dioxygenase
复制标题
DOI：
10.1016/j.jmb.2009.07.029
复制
发表时间：
2009-09-18
影响因子：
5.6
通讯作者：
Nojiri, Hideaki
中科院分区：
文献类型：
--
作者：
Inoue, Kengo;Ashikawa, Yuji;Nojiri, Hideaki
咔唑1,9a-双加氧酶（CARDO）由末端加氧酶（Oxy）、铁氧化还蛋白（Fd）和铁氧化还蛋白还原酶（Red）组成，是Rieske非血红素铁加氧酶的成员。Rieske非血红素铁加氧酶根据其成分的数量和氧化还原中心的性质分为IA、IB、IIA、IIB和III五个亚类。纯化了Nocardioides aromaticivorans IC177中IIB类CARDO的各组分，并研究了其与III类CARDO的电子转移反应的互换性。尽管这两类的Fds都是rieske型，但Oxy和Fd组分之间存在严格的特异性。另一方面，Fd和Red成分是可互换的，尽管Red成分在辅因子组成上有所不同；IIB类红色含有黄素腺嘌呤二核苷酸(FAD)-和nadh -结合结构域，而III类红色除了FAD-和nadh -结合结构域外还具有叶绿体型[2Fe-2S]簇。将IIB类Oxy和Fd组分的晶体结构与先前报道的III类CARDO的Fd:Oxy配合物结构进行比较。这一比较表明，IIB类和Ell类cardo之间的共同残基对Fd和Oxy之间的相互作用很重要。在IIB类CARDOs中，这些包括Fd中的His75和Glu71， Oxy中的Lys20和Glu357进行静电相互作用，Fd中的Phe74和Pro90以及Trp21， Leu359和Val367进行疏水相互作用。形成相互作用表面但在类之间不保守的残基被认为是形成适当的几何形状和确定Fd和Oxy之间电子转移特异性所必需的。2009爱思唯尔有限公司版权所有。
Carbazole 1,9a-dioxygenase (CARDO) consists of terminal oxygenase (Oxy), ferredoxin (Fd), and ferredoxin reductase (Red) components and is a member of the Rieske nonheme iron oxygenases. Rieske nonheme iron oxygenases are divided into five subclasses (IA, IB, IIA, IIB, and III) based on the number of constituents and the nature of their redox centers. Each component of a class IIB CARDO from Nocardioides aromaticivorans IC177 was purified, and the interchangeability of the electron transfer reactions with each component from the class III CARDOs was investigated. Despite the fact that the Fds of both classes are Rieske-type, strict specificities between the Oxy and Fd components were observed. On the other hand, the Fd and Red components were interchangeable, even though the Red components differ in cofactor composition; the class IIB Red contains flavin-adenine-dinucleotide (FAD)- and NADH-binding domains, whereas the class III Red has a chloroplast-type [2Fe-2S] cluster in addition to the FAD- and NADH-binding domains. The crystal structures of the class IIB Oxy and Fd components were compared to the previously reported Fd:Oxy complex structure of class III CARDO. This comparison suggested residues in common between class IIB and class Ell CARDOs that are important for interactions between Fd and Oxy. In the class IIB CARDOs, these included His75 and Glu71 in Fd and Lys20 and Glu357 in Oxy for electrostatic interactions, and Phe74 and Pro90 in Fd and Trp21, Leu359, and Val367 in Oxy for hydrophobic interactions. The residues that formed the interacting surface but were not conserved between classes were thought to be necessary to form the appropriate geometry and to determine electron transfer specificity between Fd and Oxy. (C) 2009 Elsevier Ltd. All rights reserved.