Wakai Satoshi, Tsujita Mizuho, Kikumoto Mei, Manchur Mohammed A, Kanao Tadayoshi, Kamimura Kazuo
Department of Botany and Microbiology, Division of Bioscience, Graduate School of Natural Science and Technology, Okayama University, Japan.
Biosci Biotechnol Biochem. 2007 Nov;71(11):2735-42. doi: 10.1271/bbb.70332. Epub 2007 Nov 7.
Sulfide:quinone oxidoreductase (SQR) was purified from membrane of acidophilic chemolithotrophic bacterium Acidithiobacillus ferrooxidans NASF-1 cells grown on sulfur medium. It was composed of a single polypeptide with an apparent molecular mass of 47 kDa. The apparent K(m) values for sulfide and ubiquinone were 42 and 14 muM respectively. The apparent optimum pH for the SQR activity was about 7.0. A gene encoding a putative SQR of A. ferrooxidans NASF-1 was cloned and sequenced. The gene was expressed in Escherichia coli as a thioredoxin-fusion protein in inclusion bodies in an inactive form. A polyclonal antibody prepared against the recombinant protein reacted immunologically with the purified SQR. Western blotting analysis using the antibody revealed an increased level of SQR synthesis in sulfur-grown A. ferrooxidans NASF-1 cells, implying the involvement of SQR in elemental sulfur oxidation in sulfur-grown A. ferrooxidans NASF-1 cells.
醌氧化还原酶（SQR）是从在硫培养基上生长的嗜酸化能自养细菌氧化亚铁硫杆菌NASF-1细胞的膜中纯化得到的。它由一条表观分子量为47 kDa的单一多肽组成。硫化物和泛醌的表观K(m)值分别为42和14 μM。SQR活性的表观最适pH约为7.0。克隆并测序了编码氧化亚铁硫杆菌NASF-1推定SQR的基因。该基因在大肠杆菌中作为硫氧还蛋白融合蛋白以无活性形式在包涵体中表达。针对重组蛋白制备的多克隆抗体与纯化的SQR发生免疫反应。使用该抗体的蛋白质印迹分析显示，在以硫生长的氧化亚铁硫杆菌NASF-1细胞中SQR合成水平增加，这意味着SQR参与了以硫生长的氧化亚铁硫杆菌NASF-1细胞中的元素硫氧化。
