Characterization and crystal structure of a novel zearalenone hydrolase from Cladophialophora bantiana

Zearalenone (ZEN) is a mycotoxin which causes huge economic losses in the food and animal feed industries. The lactonase ZHD101 from Clonostachys rosea, which catalyzes the hydrolytic degradation of ZEN, is the only known ZEN-detoxifying enzyme. Here, a protein homologous to ZHD101, denoted CbZHD, from Cladophialophora batiana was expressed and characterized. Sequence alignment indicates that CbZHD possesses the same catalytic triad and ZEN-interacting residues as found in ZHD101. CbZHD exhibits optimal enzyme activity at 35 degrees C and pH 8, and is sensitive to heat treatment. The crystal structure of apo CbZHD was determined to 1.75 angstrom resolution. The active-site compositions of CbZHD and ZHD101 were analyzed.