Franklin F C, Lehrbach P R, Lurz R, Rueckert B, Bagdasarian M, Timmis K N
J Bacteriol. 1983 May;154(2):676-85. doi: 10.1128/jb.154.2.676-685.1983.
Mutant derivatives of the TOL plasmid pWW0-161, containing Tn5 insertions in the xylS and xylR regulatory genes of the catabolic pathway, have been identified and characterized. The two genes are located together on a 1.5- to 3.0-kilobase segment of TOL, just downstream of genes of the enzymes of the meta-cleavage pathway. As predicted by a current model for regulation of the TOL catabolic pathway, benzyl alcohol dehydrogenase, a representative enzyme of the upper (hydrocarbon leads to carboxylic acid) pathway, was induced by m-methylbenzyl alcohol in xylS mutant bacteria but not in a xylR mutant, whereas catechol 2,3-oxygenase, a representative enzyme of the lower (meta-cleavage) pathway, was induced by m-toluate in a xylR mutant but not in the xylS mutants. Unexpectedly, however, catechol 2,3-oxygenase was not induced by m-methylbenzyl alcohol in xylS mutants but was induced by benzyl alcohol and benzoate. These results indicate that expression of the TOL plasmid-encoded catabolic pathway is regulated by at least three control elements, two of which (the products of the xylS and xylR genes) interact in the induction of the lower pathway by methylated hydrocarbons and alcohols and one of which responds only to nonmethylated substrates.
已鉴定并表征了TOL质粒pWW0 - 161的突变衍生物，这些衍生物在分解代谢途径的xylS和xylR调控基因中含有Tn5插入。这两个基因共同位于TOL的一个1.5至3.0千碱基片段上，就在间位裂解途径酶基因的下游。正如当前TOL分解代谢途径调控模型所预测的那样，苄醇脱氢酶是上（烃类转化为羧酸）途径的代表性酶，在xylS突变细菌中由间甲基苄醇诱导，但在xylR突变体中不被诱导；而儿茶酚2,3 - 加氧酶是下（间位裂解）途径的代表性酶，在xylR突变体中由间甲苯酸盐诱导，但在xylS突变体中不被诱导。然而，出乎意料的是，儿茶酚2,3 - 加氧酶在xylS突变体中不被间甲基苄醇诱导，但可被苄醇和苯甲酸盐诱导。这些结果表明，TOL质粒编码的分解代谢途径的表达受至少三个控制元件调控，其中两个（xylS和xylR基因的产物）在甲基化烃类和醇类诱导下途径时相互作用，另一个仅对非甲基化底物作出反应。
