Harayama S, Rekik M, Wubbolts M, Rose K, Leppik R A, Timmis K N
Department of Medical Biochemistry, Faculty of Medicine, University of Geneva, Switzerland.
J Bacteriol. 1989 Sep;171(9):5048-55. doi: 10.1128/jb.171.9.5048-5055.1989.
The upper operon of the TOL plasmid pWW0 of Pseudomonas putida encodes a set of enzymes which transform toluene and xylenes to benzoate and toluates. The genetic organization of the operon was characterized by cloning of the upper operon genes into an expression vector and identification of their products in Escherichia coli maxicells. This analysis showed that the upper operon contains at least five genes in the order of xylC-xylM-xylA-xylB-xylN. Between the promoter of the operon and xylC, there is a 1.7-kilobase-long space of DNA in which no gene function was identified. In contrast, most of the DNA between xylC and xylN consists of coding sequences. The xylC gene encodes the 57-kilodalton benzaldehyde dehydrogenase. The xylM and xylA genes encode 35- and 40-kilodalton polypeptides, respectively, which were shown by genetic complementation tests to be subunits of xylene oxygenase. The structural gene for benzyl alcohol dehydrogenase, xylB, encodes a 40-kilodalton polypeptide. The last gene of this operon is xylN, which synthesizes a 52-kilodalton polypeptide of unknown function.
恶臭假单胞菌TOL质粒pWW0的上游操纵子编码一组将甲苯和二甲苯转化为苯甲酸和甲苯酸的酶。通过将上游操纵子基因克隆到表达载体中并在大肠杆菌最大细胞中鉴定其产物，对该操纵子的遗传组织进行了表征。该分析表明，上游操纵子按xylC - xylM - xylA - xylB - xylN的顺序至少包含五个基因。在操纵子的启动子和xylC之间，有一段1.7千碱基长的DNA间隔区，在其中未鉴定到基因功能。相比之下，xylC和xylN之间的大部分DNA由编码序列组成。xylC基因编码57千道尔顿的苯甲醛脱氢酶。xylM和xylA基因分别编码35千道尔顿和40千道尔顿的多肽，遗传互补试验表明它们是二甲苯单加氧酶的亚基。苄醇脱氢酶的结构基因xylB编码一种40千道尔顿的多肽。该操纵子的最后一个基因是xylN，它合成一种功能未知的52千道尔顿的多肽。
