Identification and Biochemical Characterization of a PQQ-dependent Deoxynivalenol (DON) Dehydrogenase

Abstract

Deoxynivalenol (DON) contamination in cereals and cereal products has the potential to pose a threat to human health. The biodetoxification technique, which uses biological enzymes to transform mycotoxins into less toxic product, is an environmentally friendly and highly effective approach to detoxifying mycotoxins. In this study, a gene designated adh2, encoding DON detoxifying enzyme, was identified by homology search from the genome sequence of DON-detoxifying strain Devosia sp. FJ2-5-3. Subsequently. The adh2 gene was cloned and expressed. Then, the enzymatic properties of its encoding enzyme was further characterized. The results showed that the length of the adh2 gene in Devosia sp. FJ2-5-3 was 1770 bp and the encoded ADH2 enzyme consisted of 589 amino acids, with a signal peptide of 24 amino acids length present at the N-terminus and belonging to type I of the PQQ-dependent alcohol dehydrogenase family (Type I PQQ-ADH). The enzyme exhibited the optimal activity at pH 9 and a temperature of 35 °C, and it retained over 50% of enzyme activity after incubation at 65 ℃ for 4 hours, indicating its good thermal stability. In addition, Ca2+ was found to be an essential cofactor for ADH2, while both 1% of ethanol and isopropanol showed significant inhibitory effects on its activity. The Km and Kcat values of ADH2 for DON were 708.00±47.01 μg/mL and 3.37±0.11 S–1, respectively. These results could provide reference information for the subsequent industrial application of DON detoxification enzymes.

Keywords

• deoxynivalenol
• biodetoxification
• pqq-dependent alcohol dehydrogenase
• enzymatic property characterization