Regulation of the Enzymes of the meta-Cleavage Pathway of Pseudomonas putida: A Regulatory Model

SUMMARY: Mutants of Pseudomonas putida ncib10015 were isolated which produced catechol 2,3-oxygenase and the subsequent enzymes of the meta-cleavage pathway constitutively, and were defective in phenol hydroxylase activity. All revertants of one mutant (C3), and most revertants of a second mutant (C1), regained wild-type characteristics with respect to inducibility of phenol hydroxylase and the other meta-cleavage enzymes. Their behaviour was consistent with them being regulatory mutants. Other mutants deficient in phenol hydroxylase activity were not constitutive for catechol 2,3-oxygenase and other enzymes of the pathway. Their properties were consistent with mutations in a structural gene. A model in which phenol hydroxylase is under positive control and catechol 2,3-oxygenase and subsequent enzymes are under negative control is proposed for the regulation of enzymes of the meta-cleavage pathway in P. putida.