Enzymatic characterization of two epsilon‐class glutathione S‐transferases of Spodoptera litura

Abstract

Two cDNAs encoding glutathione S-transferase (GST) of the tobacco cutworm, Spodoptera litura, were cloned by reverse transcriptase-polymerase chain reaction. The deduced amino acid sequences of the resulting clones revealed 32-51% identities to the epsilon-class GSTs from other organisms. The recombinant proteins were functionally overexpressed in Escherichia coli cells in soluble form and were purified to homogeneity. The enzymes were capable of catalyzing the bioconjugation of glutathione with 1-chloro-2,4-dinitrobenzene, 1,2-epoxy-3-(4-nitrophenoxy)-propane, and ethacrynic acid. A competition assay revealed that the GST activity was inhibited by insecticides, suggesting that it could be conducive to insecticide tolerance in the tobacco cutworm.

Glutathione-S-Transferases in the Olfactory Organ of the Noctuid Moth Spodoptera littoralis, Diversity and Conservation of Chemosensory Clades

“…In S. littoralis , epsilon clade accounts for almost half of the described sequences, with various expression patterns ranging from ubiquitous to antennal enriched genes. SlitGSTe clustered with lepidopteran GSTe functionally involved in insecticide conjugation and protection against oxidative stress in B. mori, H. armigera, S. litura , and S. exigua (Huang et al, 2011; Yamamoto et al, 2013; Liu et al, 2015b; Xu et al, 2015; You et al, 2015; Zhou et al, 2015; Wan et al, 2016; Zhang et al, 2016; Hirowatari et al, 2017; Labade et al, 2018). Moreover, three P. xylostella GSTe are also preferentially expressed in the antennae (He et al, 2017), suggesting a potential role in olfaction.…”

Resistance in the Genus Spodoptera: Key Insect Detoxification Genes

“…In vivo studies have also confirmed the direct involvement of GSTs in insecticide tolerance. In Cheng et al, (2019), injection of siRNAi against SlGSTe20 and SlGSTe3 increased the sensitivity of S. litura larvae to imidacloprid, and the recombinant proteins subsequently showed activity towards diazinon, permethrin, chlorfenapyr, and bendiocarb [97].…”

“…In an RNAseq experiment comparing indoxacarb-resistant and susceptible S. litura populations [103], SlGSTe4 and SlGSTe20 were the only GSTs overexpressed. Interestingly, both of these GSTes are active against imidacloprid, diazinon, permethrin, chlorfenapyr, or bendiocarb [97,101], indicating potential cross-activity of SlGSTe for various insecticides. This complex pattern of gene expression regulation must be orchestrated by specific regulatory operators that can effectively govern down-or overexpression upon exposure but could also be affected by mutations in resistant strains to account for specific activations.…”

An omega‐class glutathione S‐transferase in the brown planthopper Nilaparvata lugens exhibits glutathione transferase and dehydroascorbate reductase activities

“…The resulting plasmids were transformed into E. coli , BL21 (DE3) pLysS‐competent cells (Merck Millipore, Darmstadt, Germany). The overexpression of the recombinant nlGSTO was performed according to a previous report (Hirowatari, Chen, Mita, & Yamamoto, ). The cell pellet obtained was incubated with 4 mg/ml lysozyme, and then disrupted by sonication.…”