Characterization and Functional Analysis of Four Glutathione S-Transferases from the Migratory Locust, Locusta migratoria

Abstract

Glutathione S-transferases (GSTs) play an important role in detoxification of xenobiotics in both prokaryotic and eukaryotic cells. In this study, four GSTs (LmGSTd1, LmGSTs5, LmGSTt1, and LmGSTu1) representing different classes were identified from the migratory locust, Locusta migratoria. These four proteins were heterologously expressed in Escherichia coli as soluble fusion proteins, purified by Ni2+-nitrilotriacetic acid agarose column and biochemically characterized. LmGSTd1, LmGSTs5, and LmGSTu1 showed high activities with 1-chloro-2, 4-dinitrobenzene (CDNB), detectable activity with p-nitro-benzyl chloride (p-NBC) and 1, 2-dichloro-4-nitrobenzene (DCNB), whereas LmGSTt1 showed high activity with p-NBC and detectable activity with CDNB. The optimal pH of the locust GSTs ranged between 7.0 to 9.0. Ethacrynic acid and reactive blue effectively inhibited all four GSTs. LmGSTs5 was most sensitive to heavy metals (Cu2+ and Cd2+). The maximum expression of the four GSTs was observed in Malpighian tubules and fat bodies as evaluated by western blot. The nymph mortalities after carbaryl treatment increased by 28 and 12% after LmGSTs5 and LmGSTu1 were silenced, respectively. The nymph mortalities after malathion and chlorpyrifos treatments increased by 26 and 18% after LmGSTs5 and LmGSTu1 were silenced, respectively. These results suggest that sigma GSTs in L. migratoria play a significant role in carbaryl detoxification, whereas some of other GSTs may also involve in the detoxification of carbaryl and chlorpyrifos.

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

“…Functional information regarding those clades is scarce. L. migratoria GSTu1 is expressed in Malpighian tubules and its downregulation using RNAi leads to a higher sensitivity to carbaryl and chlorpyrifos insecticides (Qin et al, 2013). In silkworm, BmGSTu2 is induced in a resistant strain and is able to conjugate glutathione to the organophosphate insecticide diazinion (Yamamoto and Yamada, 2016).…”

RNA interference of two glutathione S‐transferase genes, Diaphorina citriDcGSTe2 and DcGSTd1, increases the susceptibility of Asian citrus psyllid (Hemiptera: Liviidae) to the pesticides fenpropathrin and thiamethoxam

“…Insect GSTs, particularly the delta and epsilon classes, are known to be involved in the metabolism of both plant defense compounds and insecticides, and have been identified as an important class of detoxification enzymes . In this study, we identified and characterized one delta class ( DcGSTd1 ) and two epsilon class ( DcGSTe1 and DcGSTe2 ) GST genes in D. citri .…”

RNA interference: Applications and advances in insect toxicology and insect pest management

“…Similarly, RNAi experiments in L. migratoria nymphs resulted in significant decreases in transcript levels of GSTs5 and GSTu1 [52]. Insecticide bioassays showed that dsRNA-injected nymphs become more susceptible to carbaryl, as indicated by increases in mortality by 28 and 12%, respectively, after GSTs5 and GSTu1 were silenced.…”