Gene cloning of glutathione-S-transferase (TabsGSTs2) in Tuta absoluta and its molecular docking analysis with α-tomatine

Glutathione-S-transferases (GSTs) play an important role in insect adaptation to plant secondary metabolites. To clarify the role of the GST gene in the detoxification of Tuta absoluta to α-tomatine, we first cloned the full-length sequence of TabsGSTs2 gene. Bioinformatic analysis was employed to analyze the sequence characteristics, physicochemical properties, conserved domains, gene structure, and evolutionary relationships of the TabsGSTs2 gene. The expression levels of TabsGSTs2 under α-tomatine stress were measured using RT-qPCR, and the binding capacity and mode of TabsGSTs2 to α-tomatine were investigated using homology modeling and molecular docking. The results showed that the CDS of TabsGSTs2 was 609 bp, encoding 203 amino acids, with a theoretical isoelectric point of 8.47 and a molecular weight of 23.895 kDa. TabsGSTs2 contains four β-sheets and nine α-helices, and had the typical conserved domains of GST genes, including the GSH binding site (G-site) and the substrate binding site (H-site). Phylogenetic analysis indicated that TabsGSTs2 belongs to the sigma subfamily and was closely related to CpGSTs2 of Cydia pomonella. Under α-tomatine stress, the expression level of TabsGSTs2 was significantly higher than that of the control at 72 h. Molecular docking results suggested that TabsGSTs2 bind strongly to α-tomatine, with the interaction being stabilized primarily by hydrogen bonds, hydrophobic forces, and salt bridges. Our study provides reference for subsequent studies of the molecular mechanisms of T. absoluta adaptation to α-tomatine and provides a basis for further exploration of new targets for the control of T. absoluta.