Worsey M J, Franklin F C, Williams P A
J Bacteriol. 1978 Jun;134(3):757-64. doi: 10.1128/jb.134.3.757-764.1978.
Pseudomonas putida mt-2 carries a plasmid (TOL, pWWO) which codes for a single set of enzymes responsible for the catabolism of toluene and m- and p-xylene to central metabolites by way of benzoate and m- and p-toluate, respectively, and subsequently by a meta cleavage pathway. Characterization of strains with mutations in structural genes of this pathway demonstrates that the inducers of the enzymes responsible for further degradation of m-toluate include m-xylene, m-methylbenzyl alcohol, and m-toluate, whereas the inducers of the enzymes responsible for oxidation of m-xylene to m-toluate include m-xylene and m-methylbenzyl alcohol but not m-toluate. A regulatory mutant is described in which m-xylene and m-methylbenzyl alcohol no longer induce any of the pathway enzymes, but m-toluate is still able to induce the enzymes responsible for its own degradation. Among revertants of this mutant are some strains in which all the enzymes are expressed constitutively and are not further induced by m-xylene. A model is proposed for the regulation of the pathway in which the enzymes are in two regulatory blocks, which are under the control of two regulator gene products. The model is essentially the same as proposed earlier for the regulation of the isofunctional pathway on the TOL20 plasmid from P. putida MT20.
恶臭假单胞菌mt-2携带一个质粒（TOL，pWWO），该质粒编码一组单一的酶，这些酶分别通过苯甲酸酯和间甲苯酸酯以及对甲苯酸酯，将甲苯和间二甲苯及对二甲苯分解代谢为中心代谢物，随后通过间位裂解途径进行代谢。对该途径结构基因突变菌株的表征表明，负责间甲苯酸进一步降解的酶的诱导剂包括间二甲苯、间甲基苄醇和间甲苯酸，而负责将间二甲苯氧化为间甲苯酸的酶的诱导剂包括间二甲苯和间甲基苄醇，但不包括间甲苯酸。描述了一种调节突变体，其中间二甲苯和间甲基苄醇不再诱导该途径的任何酶，但间甲苯酸仍能够诱导负责其自身降解的酶。该突变体的回复突变体中有一些菌株，其中所有酶都是组成型表达的，并且不再被间二甲苯进一步诱导。提出了一种该途径的调节模型，其中酶处于两个调节模块中，这两个调节模块受两个调节基因产物的控制。该模型与先前提出的关于恶臭假单胞菌MT20的TOL20质粒上同功能途径调节的模型基本相同。
