Ralstonia eutropha strain E2 (previously Alcaligenes sp.) is a phenol-degrading bacterium expressing phenol-oxygenating activity with a low K (the apparent half-saturation constant in Haldane's equation) and an extremely high K (the apparent inhibition constant). To identify the molecular basis for these novel cellular kinetic properties, a 9.5 kb DNA fragment that allowed Pseudomonas aeruginosa PAO1c (Phl Cat) to grow on phenol as the sole carbon source was cloned from strain E2 into plasmid pRO1614. PAO1c harbouring this plasmid (designated pROE217) transformed phenol to catechol, indicating that this fragment contains gene(s) for phenol hydroxylase. The cloned genes consist of eight complete ORFs, designated poxRABCDEFG. The products are homologous to those of dmpRKLMNOPQ of Pseudomonas sp. CF600, sharing 30--65% identity: this suggests that the phenol hydroxylase is a multicomponent enzyme. The kinetic constants for phenol-oxygenating activity of PA01c(pROE217) were determined, and these were compared with those of strain E2. The kinetic constants of PAO1c derivatives expressing different phenol hydroxylases were also determined. A comparison of these kinetic data suggests that phenol hydroxylase, the first enzyme in the phenol-degradative pathway, determines K and K values for the cellular phenol-oxygenating activity. It is thus suggested that the phenol hydroxylase cloned from strain E2 exhibits the novel kinetic properties that were observed with intact cells of strain E2.


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error