Evolution of the cytochrome c oxidase proton pump
Evolution of the cytochrome c oxidase proton pump
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DOI：
10.1007/pl00006332
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发表时间：
1998-05-01
影响因子：
3.9
通讯作者：
Chan, SI
中科院分区：
文献类型：
--
作者：
Musser, SM;Chan, SI
喹酚和细胞色素c末端氧化酶复合体的超家族由一个同源亚基联系在一起，该亚基包含六个位置保守的组氨酸，连接着一个低自旋的血红素和一个血红素-铜氧激活和还原中心。根据这些酶的结构相似性，推测这个超家族的所有成员都通过相似的机制催化质子转移，并且大多数细胞色素c氧化酶复合体中的铜-A中心仅仅是一个电子管道，将电子从细胞色素c铁运送到酶的疏水核心。最近对细胞色素c氧化酶络合物和结构相似的没有铜-A中心的细胞色素c：一氧化氮氧化还原酶络合物的表征加强了这一观点。然而，最近的实验证据表明，在大肠杆菌细胞色素bO(3)复合体上存在两个与泛醌(Ol)池处于动态平衡的泛醌(Ol)结合部位，从而加强了质子转移的Q(H-2)环机制的论点[Musser SM等人]。(1997)生物化学36：894-902]。此外，一些报道表明，在Sulfolobus acidocaldarius末端氧化酶复合体中，Q(H-2)环或另一种不同于线粒体AA(3)型质子泵的交替质子转运机制起作用。本文探讨了一个原始的喹酚氧化酶络合物进化成两个独立的络合物的可能性，即细胞色素BC(1)和细胞色素C氧化酶络合物。这一想法是构建进化树的基础，该树使用的概念是呼吸复杂性和效率在整个进化过程中逐渐增加。分析表明，氧合呼吸是一个相当古老的过程，实际上早于氮素呼吸和反应中心光合作用。
The superfamily of quinol and cytochrome c terminal oxidase complexes is related by a homologous subunit containing six positionally conserved histidines that ligate a low-spin heme and a heme-copper dioxygen activating and reduction center. On the basis of the structural similarities of these enzymes, it has been postulated that all members of this superfamily catalyze proton translocation by similar mechanisms and that the Cu-A center found in most cytochrome c oxidase complexes serves merely as an electron conduit shuttling electrons from ferrocytochrome c into the hydrophobic core of the enzyme. The recent characterization of cytochrome c oxidase complexes and structurally similar cytochrome c:nitric oxide oxidoreductase complexes without Cu-A centers has strengthened this view. However, recent experimental evidence has shown that there are two ubiquinone(ol) binding sites on the Escherichia coli cytochrome bo(3) complex in dynamic equilibrium with the ubiquinone(ol) pool, thereby strengthening the argument for a Q(H-2)-loop mechanism of proton translocation [Musser SM et al. (1997) Biochemistry 36:894-902]. In addition, a number of reports suggest that a Q(H-2)-loop or another alternate proton translocation mechanism distinct from the mitochondrial aa(3)-type proton pump functions in Sulfolobus acidocaldarius terminal oxidase complexes. The possibility that a primitive quinol oxidase complex evolved to yield two separate complexes, the cytochrome bc(1) and cytochrome c oxidase complexes, is explored here. This idea is the basis for an evolutionary tree constructed using the notion that respiratory complexity and efficiency progressively increased throughout the evolutionary process. The analysis suggests that oxygenic respiration is quite an old process and, in fact, predates nitrogenic respiration as well as reaction-center photosynthesis.