A thermostable OTA-detoxifying hydrolase from Thermonema rossianum: identification, characterization, structure, catalytic mechanism, and application

Ochratoxin A (OTA) is highly toxic and widely distributed, posing serious threats to human and animal health. Searching for effective OTA-detoxifying enzyme is crucial for the prevention and control of OTA contaminations. Here, a new OTA-detoxifying enzyme, TrADH from Thermonema rossianum is identified, which exhibits highest temperature tolerance among OTA-detoxifying enzymes. TrADH maintains good activity in the range of 45-85 °C and retains about 50 % activity after heating at 70 °C for 30 min. Based on the solved crystal structures, the catalytic mechanism is proposed, and protein engineering of catalytic-related residues is performed to obtain a 2.1-fold upgraded variant TrADHS67E with the specific enzyme activity of 3990 U/mg, which is more efficient than the reported OTA-detoxifying enzymes. The efficient degradation of OTA in rum and walnut reveals the prospect of TrADH in food applications. The results indicate that TrADH has the potential in OTA bio-detoxification in food and feed industry.