Structural and functional characterization of ochratoxinase, a novel mycotoxin-degrading enzyme.

Dobritzsch D, Wang H, Schneider G, Yu S

Biochem. J. 462 (3) 441-452 [2014-09-15; online 2014-06-21]

Ochratoxin, with ochratoxin A as the dominant form, is one of the five major mycotoxins most harmful to humans and animals. It is produced by Aspergillus and Penicillium species and occurs in a wide range of agricultural products. Detoxification of contaminated food is a challenging health issue. In the present paper we report the identification, characterization and crystal structure (at 2.2 Å) of a novel microbial ochratoxinase from Aspergillus niger. A putative amidase gene encoding a 480 amino acid polypeptide was cloned and homologously expressed in A. niger. The recombinant protein is N-terminally truncated, thermostable, has optimal activity at pH ~6 and 66°C, and is more efficient in ochratoxin A hydrolysis than carboxypeptidase A and Y, the two previously known enzymes capable of degrading this mycotoxin. The subunit of the homo-octameric enzyme folds into a two-domain structure characteristic of a metal dependent amidohydrolase, with a twisted TIM (triosephosphateisomerase)-barrel and a smaller β-sandwich domain. The active site contains an aspartate residue for acid-base catalysis, and a carboxylated lysine and four histidine residues for binding of a binuclear metal centre.

Protein Science Facility (PSF)

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PubMed 24947135

DOI 10.1042/BJ20140382

Crossref 10.1042/BJ20140382

PDB 4C5Y

PDB 4C5Z

PDB 4C60

PDB 4C65

BJ20140382