Induction of phenol-metabolizing enzymes in Trichosporon cutaneum

Abstract

Some aspects of the induction of enzymes participating in the metabolism of phenol and resorcinol in Trichosporon cutaneum were studied using intact cells and cell-free preparations. Activities of phenol hydroxylase (1.14.13.7), catechol 1,2-oxygenase (1.13, 11.1), cis-cis-muconate cyclase (5.5.1.-), delactonizing enzyme(s) and maleolylacetate reductase were 50-400 times higher in fully induced cells than in noninduced cells. In addition to phenol and resorcinol, also catechol, cresols and fluorophenols could induce phenol hydroxylase. The induction was severely inhibited by phenol concentrations higher than 1 mM. Using optimum inducer concentrations (0.01-0.10 mM), it took more than 8 h to obtain full induction, whether in proliferating or in nonproliferating cells. Phenol hydroxylase, catechol 1,2-oxygenase and cis, cis-muconate cyclase were induced simultaneously. The synthesis of the de-lactonizing activity was delayed in relation to these three preceeding enzymes of the pathway. High glucose concentration (over 15 mM) inhibited completely the induction of phenol oxidation by nonproliferating cells. It also inhibited phenol oxidation by pre-induced cells. Among the NADPH-generating enzymes, the activity of iso-citrate dehydrogenase was elevated in cells grown on phenol and resorcinol instead of glucose.