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Molecular cloning, purification and biochemical characterization of a novel pyrethroid-hydrolyzing carboxylesterase gene from Ochrobactrum anthropi YZ-1

Zhai, Yi, Li, Kang, Song, Jinlong, Shi, Yanhua, Yan, Yanchun
Journal of hazardous materials 2012 v.221-222 pp. 206-212
Escherichia coli, Ochrobactrum anthropi, activated sludge, amino acid sequences, carboxylesterase, enzyme activity, genes, genomic libraries, molecular cloning, open reading frames, pH, pesticides, phylogeny, pyrethrins, sequence homology, substrate specificity, temperature
Strain YZ-1 was isolated from activated sludge and identified as Ochrobactrum anthropi. This strain was capable of degrading pyrethroids pesticides, suggesting the presence of degrading enzymes. In the present study, a novel esterase gene pytZ was cloned from the genomic library of YZ-1 successfully. The pytZ contained an open reading frame of 606bp encoding a pyrethroid-hydrolyzing carboxylesterase. Deduced amino acid sequence showed moderate identities (39–59%) with most homologous carboxylesterase, except a putative carboxylesterase from O. anthropi ATCC 49188 with the highest identity of 85%. Phylogenetic analysis revealed that PytZ belonged to esterase VI family. The gene pytZ showed no any sequence similarity with reported pyrethroid-hydrolyzing genes and was a new pyrethroid-degrading gene. PytZ was expressed in Escherichia coli BL21 (DE3) and purified using Ni-NTA Fast Start. PytZ was able to degrade various pyrethroids. The optimal temperature and pH were 35°C and 7.5. This enzyme was very stable over a wide range of temperature and pH. No cofactors were required for enzyme activity. Broad substrate specificity, high enzyme activity, and the favorable stability make the PytZ a potential candidate for the detoxification of pyrethroid residues in biotechnological application.