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- Title
Structural and functional characterization of ochratoxinase, a novel mycotoxin-degrading enzyme.
- Authors
DOBRITZSCH, Doreen; Huaming WANG; SCHNEIDER, Gunter; Shukun YU
- Abstract
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 Pénicillium 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 A) 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 ß-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.
- Subjects
OCHRATOXINS; MYCOTOXINS; ASPERGILLUS; PENICILLIUM; FOOD contamination; AMIDASES
- Publication
Biochemical Journal, 2014, Vol 462, Issue 3, p441
- ISSN
0264-6021
- Publication type
Article
- DOI
10.1042/BJ20140382