Glutathione S-Transferase Highly Expressed in Holotrichia parallela Antennae Inactivates the Odorant Unsaturated Aldehyde Volatiles

Abstract

Odorant-degrading enzymes in insects play a vital role in maintaining olfactory sensitivity. However, the role and molecular mechanism of glutathione S-transferases (GSTs) in odorant inactivation has been rarely studied. In the present study, 31 GSTs were identified from the antennal transcriptome of Holotrichia parallela. HpGSTd1 possesses the highest transcriptome expression level. Recombinant HpGSTd1 showed degradation activity toward various unsaturated aldehyde volatiles. Furthermore, the metabolite of cinnamaldehyde was identified by high-resolution mass spectrometry (HRMS). The molecular docking analysis and site-directed mutagenesis revealed the key residues of HpGSTd1 in degrading odorants. In addition, the unsaturated aldehyde volatiles elicited the behavioral and electrophysiological responses of H. parallela. Taken together, our findings suggest that HpGSTd1 may play an essential role in inactivating odorants in H. parallela, which provides new insights for identifying molecular targets and exploring effective olfactory regulators for this underground pest.

Functional Analysis of Insecticide Inhibition and Metabolism of Six Glutathione S-Transferases in the Rice Stem Borer, Chilo suppressalis

“…The glutathione S -transferases (GSTs, EC2.5.1.18) are a kind of multifunctional enzymes that are widely present in eukaryotes and prokaryotes including mammals, insects, bacteria, and fungi . Studies find that GSTs play various physiological roles in organisms, such as participating in antioxidation, immune responses, stress resistance, odorant degradation, and ecdysteroid biosynthesis. − Furthermore, one of the most important functions of GSTs is involved in the detoxification of numerous endogenous and exogenous compounds including drugs, insecticides, and plant allelochemicals. , In insects, GSTs are associated with the detoxification of a variety of insecticides and contribute to the resistance of insects to insecticides. ,− The GST-related resistance mechanisms in insects have been explored and four major detoxification mechanisms are revealed . First, GSTs can directly metabolize toxic substances to produce less toxic metabolites .…”