Sakamoto J, Matsumoto A, Oobuchi K, Sone N
Department of Biochemical Engineering and Science, Kyushu Institute of Technology, Fukuoka-ken, Japan.
FEMS Microbiol Lett. 1996 Oct 1;143(2-3):151-8. doi: 10.1111/j.1574-6968.1996.tb08474.x.
Gram-positive thermophilic Bacillus species contain cytochrome caa3-type cytochrome c oxidase as a terminal oxidase in the respiratory chain. To identify alternative oxidases, we isolated B. stearothermophilus mutants defective in the caa3-type oxidase activity. One mutant contained little cytochrome a and had low cytochrome c oxidase activity. However, growth and the respiratory activity of membranes in the presence of NADH were close to normal, suggesting that the mutant contains an alternative electron transfer pathway. A novel oxidase was isolated from the membrane fraction of the mutant. The enzyme is a cytochrome bd-type quinol oxidase composed of two subunits of 52 and 40 kDa, whose N-terminal regions show sequence similarity to polypeptides of the bd-type oxidase from Escherichia coli and Azotobacter vinelandii. This is the first report of a bd-type terminal oxidase purified from a Gram-positive bacterium.
革兰氏阳性嗜热芽孢杆菌在呼吸链中含有细胞色素caa3型细胞色素c氧化酶作为末端氧化酶。为了鉴定替代氧化酶，我们分离了在caa3型氧化酶活性方面有缺陷的嗜热脂肪芽孢杆菌突变体。一个突变体含有很少的细胞色素a，并且细胞色素c氧化酶活性很低。然而，在存在NADH的情况下，该突变体的生长和膜的呼吸活性接近正常，这表明该突变体含有一条替代电子传递途径。从该突变体的膜组分中分离出一种新型氧化酶。该酶是一种细胞色素bd型喹啉氧化酶，由52 kDa和40 kDa的两个亚基组成，其N端区域与来自大肠杆菌和棕色固氮菌的bd型氧化酶的多肽具有序列相似性。这是首次从革兰氏阳性细菌中纯化出bd型末端氧化酶的报道。
