Enigmatic Gratuitous Induction of the Covalent Flavoprotein Vanillyl-Alcohol Oxidase in Penicillium simplicissimum

Abstract

When Penicillium simplicissimum is grown on veratryl alcohol, anisyl alcohol, or 4-(methoxymethyl)phenol, an intracellular covalent flavin-containing vanillyl-alcohol oxidase is induced. The induction is highest (up to 5% of total protein) during the growth phase. In addition to vanillyl-alcohol oxidase, an intracellular catalase-peroxidase is induced. Induction of vanillyl-alcohol oxidase in P. simplicissimum is prevented by the addition of isoeugenol to veratryl alcohol-containing media, but growth is unaffected. The inhibitory effect of isoeugenol on induction is not observed when anisyl alcohol or 4-(methoxymethyl)phenol is used as the growth substrate. Based on the induction experiments and the degradation pathways for veratryl and anisyl alcohol, we propose that induction of vanillyl-alcohol oxidase is superfluous when P. simplicissimum is grown on these aromatic alcohols. However, the enzyme plays an essential role in the degradation of the methyl ether of p-cresol, 4-(methoxymethyl)phenol.