Don R H, Weightman A J, Knackmuss H J, Timmis K N
J Bacteriol. 1985 Jan;161(1):85-90. doi: 10.1128/jb.161.1.85-90.1985.
Plasmid pJP4 permits its host bacterium, strain JMP134, to degrade and utilize as sole sources of carbon and energy 3-chlorobenzoate and 2,4-dichlorophenoxyacetic acid (R. H. Don and J. M. Pemberton, J. Bacteriol. 145:681-686, 1981). Mutagenesis of pJP4 by transposons Tn5 and Tn1771 enabled localization of five genes for enzymes involved in these catabolic pathways. Four of the genes, tfdB, tfdC, tfdD, and tfdE, encoded 2,4-dichlorophenol hydroxylase, dichlorocatechol 1,2-dioxygenase, chloromuconate cycloisomerase, and chlorodienelactone hydrolase, respectively. No function has been assigned to the fifth gene, tfdF, although it may encode a trans-chlorodiene-lactone isomerase. Inactivation of genes tfdC, tfdD, and tfdE, which encode the transformation of dichlorocatechol to chloromaleylacetic acid, prevented host strain JMP134 from degrading both 3-chlorobenzoate and 2,4-dichlorophenoxyacetic acid, which indicates that the pathways for these two substrates utilize common enzymes for the dissimilation of chlorocatechols. Studies with cloned catabolic genes from pJP4 indicated that whereas all essential steps in the degradation of 2,4-dichlorophenoxyacetic acid are plasmid encoded, the conversion of 3-chlorobenzoate to chlorocatechol is specified by chromosomal genes.
质粒pJP4可使其宿主细菌JMP134菌株降解并利用3 - 氯苯甲酸和2,4 - 二氯苯氧基乙酸作为唯一的碳源和能源（R. H. 唐和J. M. 彭伯顿，《细菌学杂志》145:681 - 686, 1981）。通过转座子Tn5和Tn1771对pJP4进行诱变，使得参与这些分解代谢途径的五种酶的基因得以定位。其中四个基因，tfdB、tfdC、tfdD和tfdE，分别编码2,4 - 二氯苯酚羟化酶、二氯儿茶酚1,2 - 双加氧酶、氯粘康酸环异构酶和氯二烯内酯水解酶。虽然第五个基因tfdF可能编码反式氯二烯内酯异构酶，但尚未确定其功能。编码二氯儿茶酚向氯马来酰乙酸转化的基因tfdC、tfdD和tfdE的失活，阻止了宿主菌株JMP134降解3 - 氯苯甲酸和2,4 - 二氯苯氧基乙酸，这表明这两种底物的代谢途径利用共同的酶来异化氯儿茶酚。对来自pJP4的克隆分解代谢基因的研究表明，虽然2,4 - 二氯苯氧基乙酸降解的所有关键步骤都是由质粒编码的，但3 - 氯苯甲酸向氯儿茶酚的转化是由染色体基因决定的。
