Structural highlights
Publication Abstract from PubMedOchratoxin A (OTA) is among the most prevalent mycotoxins detected in agroproducts, posing serious threats to human and livestock health. Using enzymes to conduct OTA detoxification is an appealing potential strategy. The recently identified amidohydrolase from Stenotrophomonas acidaminiphila, termed ADH3, is the most efficient OTA-detoxifying enzyme reported thus far and can hydrolyze OTA to nontoxic ochratoxin alpha (OTalpha) and L-beta-phenylalanine (Phe). To elucidate the catalytic mechanism of ADH3, we solved the single-particle cryo-electron microscopy (cryo-EM) structures of apo-form, Phe- and OTA-bound ADH3 to an overall resolution of 2.5-2.7 A. The role of OTA-binding residues was investigated by structural, mutagenesis and biochemical analyses. We also rationally engineered ADH3 and obtained variant S88E, whose catalytic activity was elevated by 3.7-fold. Structural analysis of variant S88E indicates that the E88 side chain provides additional hydrogen bond interactions to the OTalpha moiety. Furthermore, the OTA-hydrolytic activity of variant S88E expressed in Pichia pastoris is comparable to that of Escherichia coli-expressed enzyme, revealing the feasibility of employing the industrial yeast strain to produce ADH3 and its variants for further applications. These results unveil a wealth of information about the catalytic mechanism of ADH3-mediated OTA degradation and provide a blueprint for rational engineering of high-efficiency OTA-detoxifying machineries. Cryo-EM structure and rational engineering of a superefficient ochratoxin A-detoxifying amidohydrolase.,Dai L, Niu D, Huang JW, Li X, Shen P, Li H, Xie Z, Min J, Hu Y, Yang Y, Guo RT, Chen CC J Hazard Mater. 2023 Sep 15;458:131836. doi: 10.1016/j.jhazmat.2023.131836. Epub , 2023 Jun 12. PMID:37331057[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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