Santana M, Kunst F, Hullo M F, Rapoport G, Danchin A, Glaser P
Unité de Régulation de l'Expression Génétique, Institut Pasteur, Paris, France.
J Biol Chem. 1992 May 25;267(15):10225-31.
Bacillus subtilis contains two aa3-type terminal oxidases (caa3-605 and aa3-600) catalyzing cytochrome c and quinol oxidation, respectively, with the concomitant reduction of O2 to H2O (Lauraeus, M., Haltia, T., Saraste, M., and Wikström, M. (1991) Eur. J. Biochem. 197, 699-705). Previous studies characterized only the structural genes of caa3-605 oxidase. We isolated the genes coding for the four subunits of a B. subtilis terminal oxidase from a genomic DNA library. These genes, named qoxA to qoxD, are organized in an operon. Examination of the deduced amino acid sequence of Qox subunits showed that this oxidase is structurally related to the large family of mitochondrial-type aa3 terminal oxidases. In particular, the amino acid sequences are very similar to those of subunits of Escherichia coli bo quinol oxidase and B. subtilis caa3-605 cytochrome c oxidase. We produced, by in vitro mutagenesis, a mutation in the qox operon. From the phenotype of the mutant strain devoid of Qox protein, the study of expression of the qox operon in different growth conditions, and the analysis of the deduced amino acid sequence of the subunits, we concluded that Qox protein and aa3-600 quinol oxidase are the same protein. Although several terminal oxidases are found in B. subtilis, Qox oxidase (aa3-600) is predominant during the vegetative growth and its absence leads to important alterations of the phenotype of B. subtilis.
枯草芽孢杆菌含有两种aa3型末端氧化酶（caa3-605和aa3-600），分别催化细胞色素c和喹啉氧化，同时将O2还原为H2O（劳拉厄斯，M.，哈尔蒂亚，T.，萨拉斯特，M.，和维克斯特伦，M.（1991年）《欧洲生物化学杂志》197，699-705）。先前的研究仅对caa3-605氧化酶的结构基因进行了表征。我们从基因组DNA文库中分离出编码枯草芽孢杆菌一种末端氧化酶四个亚基的基因。这些基因命名为qoxA至qoxD，它们以操纵子的形式排列。对Qox亚基推导的氨基酸序列的研究表明，这种氧化酶在结构上与线粒体型aa3末端氧化酶的大家族相关。特别是，氨基酸序列与大肠杆菌bo喹啉氧化酶和枯草芽孢杆菌caa3-605细胞色素c氧化酶的亚基非常相似。我们通过体外诱变在qox操纵子中产生了一个突变。从缺乏Qox蛋白的突变菌株的表型、qox操纵子在不同生长条件下的表达研究以及亚基推导氨基酸序列的分析，我们得出结论，Qox蛋白和aa3-600喹啉氧化酶是同一种蛋白。尽管在枯草芽孢杆菌中发现了几种末端氧化酶，但Qox氧化酶（aa3-600）在营养生长期间占主导地位，其缺失会导致枯草芽孢杆菌表型的重要改变。
