Induction and inactivation of phenol hydroxylase and catechol oxygenase in Candida maltosa L4 in dependence on the carbon source
✍ Scribed by Dr. K. H. Hofmann; Anne-Kathrin Krüger
- Publisher
- John Wiley and Sons
- Year
- 1985
- Tongue
- English
- Weight
- 425 KB
- Volume
- 25
- Category
- Article
- ISSN
- 0233-111X
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✦ Synopsis
In order to investigate the regulation of phenol assimilation in the yeast Candida maltosa L4 the activities of phenol hydroxylase and catechol oxygenase were measured in crude extracts from cells grown in presence of different carbon sources.
No activities of these two enzymes have been found in cells grown on glucoae, glycerol, succinate
or n-hexadecane. The phenol hydroxylase and catechol oxygenase were induced in presence of phenol. Glucose repressed the induction of both enzymes. The catechol oxygenare appeared only after complete exhaustion of glucose and in the presence of phenol. The phenol hydroxylase was already synthesized in preeence of Icw ccncentraticrs cf glnccre (< O.ro/, w/v). Addition of glucose (2% w/v) to a culture of Candida maltosa L4 caused a very rapid disappearance of phenol hydroxylase activity both in the presence cf phenol or after depletion of phenol.
The catechol oxygenase activity decreased only slowly under these conditions. The inactivation of phenol hydroxylase could be reversed by transferring the glucose-treated cells into a glucose-free and phenol-containing medium. This reappearance of phenol hydroxylase activity could be prevented by the addition of 0.1 mM of cycloheximid, it is, therefore, dependent on de nova protein synthesis.
From these results we conclude that the glucose-dependent catabolite inactivation of phenol hydroxylase in Candida rnaltosa L4 resulted in a proteolytic degradation of the enzyme.