Abstract:
Carposina sasakii is a major fruit-boring pest in deciduous fruit trees. To investigate the role of GST in the detoxification metabolism of abamectin in
C. sasakii, we employed a droplet method to analyze the toxicity of abamectin to third-instar larvae. The change in GST enzyme activity following treatment with the median lethal concentration (LC
50) of abamectin was examined. Molecular docking was used to analyze the binding interaction between CsGSTε1 and abamectin. The CsGSTε1 protein was heterologously expressed in
Escherichia coli, and its catalytic activity and inhibitory potential by abamectin were analyzed. The enzyme kinetics of the recombinant CsGSTε1 protein was determined using 1-chloro-2,4-dinitrobenzene (CDNB) as a substrate, while the metabolic effect of CsGSTε1 towards abamectin was analyzed using ultra-high performance liquid chromatography (UHPLC). The results showed that the LC
50 value of abamectin for third-instar larvae was 10.19 mg/L. After treatment with abamectin, the GST enzyme activity in larvae significantly increased. Among 14
GST genes,
CsGSTε1 was the most highly induced and upregulated (6.03-fold) . The recombinant CsGSTε1 protein was successfully expressed in
E. coli, yielding 0.36 μg/μL, with a
Km of (683.50 ± 47.9) μmol/L and a
Vmax of (1538.0 ± 105.4) μmol/(min∙mg), indicating good catalytic activity. The half maximal inhibitory concentration (IC
50) of abamectin for CsGSTε1 was determined to be 60.4 μmol/L. The metabolic assays indicated that recombinant CsGSTε1 has metabolic activity toward abamectin. The findings of this study lay a foundation for further analysis of the role of GST in metabolic resistance to the insecticide in the peach fruit borer.