Cardiolipin deficiency causes a dissociation of the b 6 c:caa 3 megacomplex in B-subtilis membranes
Cardiolipin deficiency causes a dissociation of the b 6 c:caa 3 megacomplex in B-subtilis membranes
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DOI：
10.1007/s10863-016-9671-y
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发表时间：
2016-08-01
影响因子：
3
通讯作者：
Berta Gutierrez-Cirlos, Emma
中科院分区：
文献类型：
--
作者：
Garcia Montes de Oca, Led Yered Jafet;Cabellos Avelar, Tecilli;Berta Gutierrez-Cirlos, Emma
能量转导膜中呼吸复合体之间的联系已经建立。事实上，已知革兰氏阴性菌脱氮副球藻和大肠杆菌在其膜上具有呼吸超复合体。这些超复合体对于代谢途径中酶之间的底物通道是重要的，这些超复合体的组装依赖于蛋白质亚单位和膜脂，主要是存在于线粒体内膜和细菌膜中的心磷脂。革兰氏阳性细菌枯草芽孢杆菌有一个分支呼吸链，其中一些复合体产生质子动力，而另一些复合体则构成过剩还原能力的逃逸阀门。这种呼吸链的一些特性如下：II型NADH脱氢酶，一个独特的b(6)c复合体，它具有一个b(6)型细胞色素与共价结合的血红素，以及一个连接到第三亚单位的c型血红素，它类似于光合作用b(6)f复合体的亚基IV。细胞色素c氧还原酶(CAA(3))在亚基I上含有一个c型细胞色素。我们以前发现b(6)c与CAA(3)形成一个超络合物。B(6)C和CAA(3)与苯二酚氧还原酶AA(3)一起在枯草杆菌中产生质子动力。为了寻找这种超复合体对细菌在有氧条件下生长的重要性的证据，我们比较了来自野生型膜的b(6)c：CaA(3)超复合体和来自两个缺乏心磷脂的突变体的膜。两个突变复合体的活性和血红素含量都与野生型相似。清晰的天然电泳法显示，缺乏心磷脂的突变体经洋地黄素膜增溶后，有较小质量的b(6)c：CaA(3)超络合物，甚至有单独的络合物。十二烷基麦芽糖苷的使用揭示了野生型和突变型超复合体之间的更明显的差异。在这里，我们提供的证据表明，心磷脂在枯草杆菌中b(6)c：CaA(3)超复合体的稳定性中起作用。
The associations among respiratory complexes in energy-transducing membranes have been established. In fact, it is known that the Gram-negative bacteria Paracoccus denitrificans and Escherichia coli have respiratory supercomplexes in their membranes. These supercomplexes are important for channeling substrates between enzymes in a metabolic pathway, and the assembly of these supercomplexes depends on the protein subunits and membrane lipids, mainly cardiolipin, which is present in both the mitochondrial inner membrane and bacterial membranes. The Gram-positive bacterium Bacillus subtilis has a branched respiratory chain, in which some complexes generate proton motive force whereas others constitute an escape valve of excess reducing power. Some peculiarities of this respiratory chain are the following: a type II NADH dehydrogenase, a unique b (6) c complex that has a b (6) type cytochrome with a covalently bound heme, and a c-type heme attached to the third subunit, which is similar to subunit IV of the photosynthetic b (6) f complex. Cytochrome c oxygen reductase (caa (3) ) contains a c-type cytochrome on subunit I. We previously showed that the b (6) c and the caa (3) complexes form a supercomplex. Both the b (6) c and the caa (3) together with the quinol oxygen reductase aa (3) generate the proton motive force in B. subtilis. In order to seek proof that this supercomplex is important for bacterial growth in aerobic conditions we compared the b (6) c: caa (3) supercomplex from wild type membranes with membranes from two mutants lacking cardiolipin. Both mutant complexes were found to have similar activity and heme content as the wild type. Clear native electrophoresis showed that mutants lacking cardiolipin had b (6) c:caa (3) supercomplexes of lower mass or even individual complexes after membrane solubilization with digitonin. The use of dodecyl maltoside revealed a more evident difference between wild-type and mutant supercomplexes. Here we provide evidence showing that cardiolipin plays a role in the stability of the b (6) c:caa (3) supercomplex in B. subtilis.