Identification and molecular characterization of vinyl phenol reductase from D. bruxellensis CBS 4481

19 strains of Dekkera bruxellensis were screened for vinyl phenol reductase (VPR) activity. Presence/absence of the precursors in the growth medium gave no significant differences in VPR activity, confirming that this enzyme is constitutively expressed. A purified protein with VPR activity was extracted from D. bruxellensis CBS 4481 cells. The amino acidic sequence, achieved by trypsinolysis and mass spectrometry, revealed a high homology with a Cu/Zn superoxide dismutase (SOD) in the D. bruxellensis AWRI 1499 genome. Actually, the isolated protein possessed both vinyl phenol reductase and superoxide dismutase activities. The bioinformatics analysis showed the presence of cofactor-binding sites, that are absent or severely altered in sequences of superoxide dismutases from other wine-relevant yeast species, which do not display vinyl phenol reduction. This moonlighting activity of D. bruxellensis SOD as a VPR is related to its capacity of catalyzing NADH-dependent reduction of vinyl phenols.