The 'antiporter module' of respiratory chain Complex I includes the MrpC/NuoK subunit -: a revision of the modular evolution scheme-猫眼课题宝

DOI：

10.1016/s0014-5793(03)00767-1

发表时间：

2003-08-14

期刊：

FEBS LETTERS

影响因子：

3.5

通讯作者：

中科院分区：

生物学3区

文献类型：

--

作者：

Mathiesen, C;Hägerhäll, C

呼吸链复合物I或NADH：醌氧化还原酶催化线粒体基质或细菌细胞质中NADH的氧化和膜中醌的还原，与跨膜泵送4 H（+）/2 e（-）偶联。相同的酶复合物也能够进行逆反应，即Deltamu（H）（+）-支持的NAD（+）还原。耦合电子转移质子泵的分子机制还不清楚。复合物I酶含有14个功能所必需的蛋白质亚基，是从较小的功能构建块进化而来的。三个复合物I蛋白亚基，NuoL，NuoM和NuoN，显示出与一类特定的反向转运蛋白的主要序列相似性，因此预测在质子转运机制中发挥作用。这些反向转运蛋白MrpA和MrpD由一个保守的基因簇编码，该基因簇包含7个基因。在以前的工作中，我们已经确定这些反向转运蛋白分为两个亚类，MrpA型和MrpD型，并且复合物I亚基NuoL与MrpA更密切相关，NuoM和N与MrpD反向转运蛋白更密切相关。这意味着MrpA和MrpD都被募集到复合体I中，而不是由一个反向转运蛋白编码基因的基因复制产生。在这项工作中，我们表明，MrpC和NuoK是同源蛋白。对这些发现最合理的解释是多亚基反向转运蛋白复合物被募集到祖先酶中。我们进一步得出结论，复合物I酶家族和膜结合型NiFe氢化酶3和4的最后共同祖先含有NuoKLMN亚基模块。(C)2003年由Elsevier B. V.代表欧洲生物化学学会联合会出版。

Respiratory chain Complex I or NADH:quinone oxidoreductase catalyzes oxidation of NADH in the mitochondrial matrix or bacterial cytoplasm and reduction of quinone in the membrane, coupled to pumping of 4H(+)/2e(-) across the membrane. The same enzyme complex is also capable of the reverse reaction, i.e. Deltamu(H)(+)-supported NAD(+) reduction. The molecular mechanism that couples electron transfer to proton pumping is not understood. The Complex I enzyme, containing 14 protein subunits necessary for function, has evolved from smaller functional building blocks. Three Complex I protein subunits, NuoL, NuoM and NuoN, show primary sequence similarity to one particular class of antiporters, and are thus predicted to play a role in the proton translocation machinery. These antiporters, MrpA and MrpD are encoded by a conserved gene cluster, that contains seven genes. In previous work we have determined that these antiporters come in two subclasses, MrpA-type and MrpD-type, and that the Complex I subunit NuoL is more closely related to MrpA and NuoM and N are more closely related to the MrpD antiporter. This implied that both MrpA and MrpD had been recruited to Complex I, rather than arising from gene duplications of one antiporter encoding gene. In this work we show that MrpC and NuoK are homologous proteins. The most plausible explanation for these findings is that a multisubunit antiporter complex was recruited to the ancestral enzyme. We further conclude that the last common ancestor of the Complex I enzyme family and membrane bound NiFe hydrogenases of type 3 and 4 contained the NuoKLMN subunit module. (C) 2003 Published by Elsevier B.V. on behalf of the Federation of European Biochemical Societies.