Lübben M, Kolmerer B, Saraste M
European Molecular Biology Laboratory, Heidelberg, FRG.
EMBO J. 1992 Mar;11(3):805-12. doi: 10.1002/j.1460-2075.1992.tb05117.x.
The operon coding for a respiratory quinol oxidase was cloned from thermoacidophilic archaebacterium Sulfolobus acidocaldarius. It contains three genes, soxA, soxB and soxC. The first two genes code for proteins related to the cytochrome c oxidase subunits II and I, respectively. soxC encodes a protein homologous to cytochrome b, which is a subunit of the mitochondrial and bacterial cytochrome c reductases and the chloroplast cytochrome b6f complex. soxA is preceded by a promoter and the genes are cotranscribed into a 4 kb mRNA. Their protein products form a complex which has been partially purified and has quinol oxidase activity. The reduced minus oxidized absorption spectrum of the complex has two maxima at 586 and 606 nm. The latter is typical of cytochrome c oxidase. The complex contains four haems A. Two haems belong to the 'cytochrome oxidase' part of the complex and two are probably bound to be apocytochrome b (SoxC) and responsible for the 586 nm absorption peak. The homology between the sox gene products and their mitochondrial counterparts suggests that energy conservation coupled to the quinol oxidation catalysed either by the Sulfolobus oxidase or two mitochondrial respiratory enzymes may have a similar mechanism.
编码呼吸喹啉氧化酶的操纵子是从嗜热嗜酸古细菌嗜酸硫化叶菌中克隆出来的。它包含三个基因，soxA、soxB和soxC。前两个基因分别编码与细胞色素c氧化酶亚基II和I相关的蛋白质。soxC编码一种与细胞色素b同源的蛋白质，细胞色素b是线粒体和细菌细胞色素c还原酶以及叶绿体细胞色素b6f复合物的一个亚基。soxA之前有一个启动子，这些基因被共转录成一个4 kb的mRNA。它们的蛋白质产物形成一个复合物，该复合物已被部分纯化并具有喹啉氧化酶活性。该复合物的还原态减去氧化态吸收光谱在586和606 nm处有两个最大值。后者是细胞色素c氧化酶的典型特征。该复合物含有四个血红素A。两个血红素属于复合物的“细胞色素氧化酶”部分，另外两个可能与脱辅基细胞色素b（SoxC）结合，并负责586 nm的吸收峰。sox基因产物与其线粒体对应物之间的同源性表明，与嗜酸硫化叶菌氧化酶或两种线粒体呼吸酶催化的喹啉氧化相关的能量守恒可能具有类似的机制。
