Cloning of a Novel Pyrethroid-Hydrolyzing Carboxylesterase Gene from Sphingobium sp Strain JZ-1 and Characterization of the Gene Product

A novel esterase gene, pytH, encoding a pyrethroid-hydrolyzing carboxylesterase was cloned from Sphingobium sp. strain JZ-1. The gene contained an open reading frame of 840 bp. Sequence identity searches revealed that the deduced enzyme shared the highest similarity with many alpha/beta-hydrolase fold proteins ( 20 to 24% identities). PytH was expressed in Escherichia coli BL21 and purified using Ni-nitrilotriacetic acid affinity chromatography. It was a monomeric structure with a molecular mass of approximately 31 kDa and a pI of 4.85. PytH was able to transform p-nitrophenyl esters of short-chain fatty acids and a wide range of pyrethroid pesticides, and isomer selectivity was not observed. No cofactors were required for enzyme activity.