Liu_2023_J.Hazard.Mater_451_131128

The long-term and excessive use of pyrethroid pesticides poses substantial health risks and ecosystem concerns. Several bacteria and fungi have been reported that could degrade pyrethroids. The ester-bond hydrolysis using hydrolases is the initial regulatory metabolic reaction of pyrethroids. However, the thoroughly biochemical characterization of hydrolases involved in this process is limited. Here, a novel carboxylesterase, designated as EstGS1 that could hydrolyze pyrethroid pesticides was characterized. EstGS1 showed low sequence identity (<27.03%) compared to other reported pyrethroid hydrolases and belonged to the hydroxynitrile lyase family that preferred short short-chain acyl esters (C2 to C8). EstGS1 displayed the maximal activity of 213.38 U/mg at 60 degreesC and pH 8.5 using pNPC2 as substrate, with K(m) and V(max) were 2.21 +/- 0.72 mM and 212.90 +/- 41.78 microM/min, respectively. EstGS1 is a halotolerant esterase and remains stable in 5.1 M NaCl. Based on molecular docking and mutational analysis, the catalytic triad of S(74)-D(181)-H(212) and three other substrate-binding residues I(108), S(159), and G(75) are critical for the enzymatic activity of EstGS1. Additionally, 61 and 40 mg/L of deltamethrin and lambda-cyhalothrin were hydrolyzed by 20 U of EstGS1 in 4 h. This work presents the first report on a pyrethroid pesticide hydrolase characterized from a halophilic actinobacteria.