Blümel Silke, Knackmuss Hans-Joachim, Stolz Andreas
Institut für Mikrobiologie der Universität Stuttgart, 70569 Stuttgart, Germany.
Appl Environ Microbiol. 2002 Aug;68(8):3948-55. doi: 10.1128/AEM.68.8.3948-3955.2002.
The gene coding for an aerobic azoreductase was cloned from Xenophilus azovorans KF46F (formerly Pseudomonas sp. strain KF46F), which was previously shown to grow with the carboxylated azo compound 1-(4'-carboxyphenylazo)-2-naphthol (carboxy-Orange II) as the sole source of carbon and energy. The deduced amino acid sequence encoded a protein with a molecular weight of 30,278 and showed no significant homology to amino acid sequences currently deposited at the relevant data bases. A presumed NAD(P)H-binding site was identified in the amino-terminal region of the azoreductase. The enzyme was heterologously expressed in Escherichia coli and the azoreductase activities of resting cells and cell extracts were compared. The results suggested that whole cells of the recombinant E. coli strains were unable to take up sulfonated azo dyes and therefore did not show in vivo azoreductase activity. The turnover of several industrially relevant azo dyes by cell extracts from the recombinant E. coli strain was demonstrated.
编码需氧偶氮还原酶的基因是从偶氮食酸菌KF46F（以前称为假单胞菌属菌株KF46F）中克隆得到的，该菌株先前已被证明能够以羧化偶氮化合物1-（4'-羧基苯基偶氮）-2-萘酚（羧基橙II）作为唯一碳源和能源进行生长。推导的氨基酸序列编码了一种分子量为30278的蛋白质，并且与目前保存在相关数据库中的氨基酸序列没有显著同源性。在偶氮还原酶的氨基末端区域鉴定出一个推测的NAD(P)H结合位点。该酶在大肠杆菌中进行了异源表达，并比较了静息细胞和细胞提取物的偶氮还原酶活性。结果表明，重组大肠杆菌菌株的全细胞无法摄取磺化偶氮染料，因此在体内未表现出偶氮还原酶活性。证明了重组大肠杆菌菌株的细胞提取物对几种工业相关偶氮染料具有催化活性。
