The F420H2 dehydrogenase from Methanosarcina mazei is a redox-driven proton pump closely related to NADH dehydrogenases
The F420H2 dehydrogenase from Methanosarcina mazei is a redox-driven proton pump closely related to NADH dehydrogenases
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DOI：
10.1074/jbc.m000650200
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发表时间：
2000-06-16
影响因子：
4.8
通讯作者：
Deppenmeier, U
中科院分区：
文献类型：
--
作者：
Bäumer, S;Ide, T;Deppenmeier, U
F420H2 脱氢酶是产甲烷古菌 Methanosarcina mazei Gal 的能量守恒电子传输系统的一部分，本文显示，膜结合酶催化的辅因子 F420H2 依赖性 2-羟基吩嗪还原与跨细胞质膜的质子易位耦合，表现出每两个电子转移 0.9 个 H+ 易位的化学计量。由此产生的电化学质子梯度被证明可以驱动 ADP + Pi 合成 ATP。编码 M. mazei Gol 的 F420H2 脱氢酶的基因簇包含 12 个基因，分别称为 fpoA、B、C、D、H、I、J、K、L、M、N 和 O。对推导的氨基酸序列的分析表明，该酶与细菌（NDH-1）和真核生物（复合体 I）呼吸链的质子易位 NADH 脱氢酶密切相关。与 NADH 依赖性酶一样，F420H2 脱氢酶由三个亚复合物组成。基因产物 FpoA、EF、J、K、L、M 和 N 具有高度疏水性，与形成 NDH-1 膜积分模块的亚基同源。 FpoB、C、D 和 I 在 NDH-1 的两亲膜相关模块中具有对应物。 M. mazei Gill 中不存在亲水性 NADH 氧化输入模块的同源物，相反，基因产物 FpoF 负责 F420H2 氧化并可能充当电子输入部分。因此，来自 M. mazei Gol 的 F420H2 脱氢酶在许多方面类似于真核和细菌质子转移 NADH 脱氢酶。来自产甲烷古菌的酶作为 NDB-1/复合物 I 同系物发挥作用，并配备了用于氧化还原型辅因子 F-420 的替代电子输入单元和用于还原吩嗪的改良输出模块。
The F420H2 dehydrogenase is part of the energy conserving electron transport system of the methanogenic archaeon Methanosarcina mazei Gal, Here it is shown that cofactor F420H2-dependent reduction of 2-hydroxy-phenazine as catalyzed by the membrane-bound enzyme is coupled to proton translocation across the cytoplasmic membrane, exhibiting a stoichiometry of 0.9 H+ translocated per two electrons transferred. The electrochemical proton gradient thereby generated was shown to drive ATP synthesis from ADP + Pi. The gene cluster encoding the F420H2 dehydrogenase of M. mazei Gol comprises 12 genes that are referred to as fpoA, B, C, D, H, I, J, K, L, M, N, and O. Analysis of the deduced amino acid sequences revealed that the enzyme is closely related to proton translocating NADH dehydrogenases of respiratory chains from bacteria (NDH-1) and eukarya (complex I). Like the NADH-dependent enzymes, the F420H2 dehydrogenase is composed of three subcomplexes. The gene products FpoA, EF, J, K, L, M, and N are highly hydrophobic and are homologous to subunits that form the membrane integral module of NDH-1. FpoB, C, D, and I have their counterparts in the amphipathic membrane-associated module of NDH-1. Homologues to the hydrophilic NADH-oxidizing input module are not present in M. mazei Gill, Instead, the gene product FpoF maS be responsible for F420H2 oxidation and may function as the electron input part, Thus, the F420H2 dehydrogenase from M. mazei Gol resembles eukaryotic and bacterial proton transiocating NADH dehydrogenases in many ways. The enzyme from the methanogenic archaeon functions as a NDB-1/complex I homologue and is equipped with an alternative electron input unit for the oxidation of reduced cofactor F-420 and a modified output module adopted to the reduction of methanophenazine.