D3404: Contribution of glutathione S-transferases in chemical adaptation of Apis mellifera

The Western honey bee, Apis mellifera, is the principle managed pollinator species across the world. In recent decades, honey bee populations are facing serious health threats from combined biotic and abiotic stress including diseases, limited nutrition, and environmental chemicals. Evidence has shown that A. mellifera is extensively exposed to numerous pesticides, plant allelochemicals, and pollutants present in flowers, propolis, hives and other environmental routes. However, there is a huge knowledge gap in understanding molecular mechanisms involved in chemical adaptation of A. mellifera. Glutathione S-transferases (GSTs) are a family of multifunctional enzymes present in both eukaryotes and prokaryotes. They play an important role in the detoxification of endogenous and xenobiotic compounds helping organisms to adapt to their chemical environment. The major mechanisms of GST-mediated chemical detoxification in insects include direct metabolism, sequestration, and antioxidant activity against oxidative stress. One or more of these mechanisms can be involved in the development of pesticide resistance and host plant adaptation in agricultural pests. The evolution of the different honey bee GST classes indicates their diverse roles in the detoxification of a wide range of toxic chemicals in the environment. The functional diversity of honey bee GST enzymes lies in the variety of structure and composition of their amino acid residues constituted in their active sites. Recent availability of whole genome sequences, X-ray crystallography, enzyme kinetics and site-directed mutagenesis techniques have significantly enhanced our understanding of functional and structural diversity of honey bee GSTs in chemical adaptation.