Lübben M, Arnaud S, Castresana J, Warne A, Albracht S P, Saraste M
European Molecular Biology Laboratory, Heidelberg, Germany.
Eur J Biochem. 1994 Aug 15;224(1):151-9. doi: 10.1111/j.1432-1033.1994.tb20006.x.
We previously found that the soxABCD operon encodes a quinol oxidase complex in Sulfolobus acidocaldarius and this enzyme was purified and characterized. In this study, we have used a cloning procedure based on the conservation of oxidase sequences and the polymerase chain reaction to isolate a new gene (soxM) encoding a subunit of another terminal oxidase. This terminal oxidase is a fusion between two central components of cytochrome oxidases, subunits I and III. soxM forms a transcriptional unit which is expressed under heterotrophic growth conditions. The corresponding protein was detected by direct protein sequencing in a preparation enriched with a cytochrome absorbing light at 562 nm. This preparation contains a terminal oxidase which is able to oxidize the artificial substrate N,N,N',N'-tetramethyl-p-phenylenediamine. This preparation also contains SoxC, a protein homologous to the mitochondrial cytochrome b, and a Rieske iron-sulphur center. We suggest that SoxM is the core component of a second terminal oxidase complex and that this complex may share a subunit (SoxC) with the SoxABCD complex.
我们先前发现，soxABCD操纵子在嗜酸热硫化叶菌中编码一种喹啉氧化酶复合物，并且该酶已被纯化和表征。在本研究中，我们基于氧化酶序列的保守性和聚合酶链反应，采用克隆程序分离出一个编码另一种末端氧化酶亚基的新基因（soxM）。这种末端氧化酶是细胞色素氧化酶的两个核心组分，即亚基I和亚基III的融合体。soxM形成一个转录单元，在异养生长条件下表达。通过直接蛋白质测序在富含在562nm处吸收光的细胞色素的制剂中检测到了相应的蛋白质。该制剂含有一种能够氧化人工底物N，N，N'，N'-四甲基对苯二胺的末端氧化酶。该制剂还含有与线粒体细胞色素b同源的蛋白质SoxC和一个 Rieske 铁硫中心。我们认为SoxM是第二种末端氧化酶复合物的核心组分，并且该复合物可能与SoxABCD复合物共享一个亚基（SoxC）。
