Protection of HSP60 in Myzus persicae Treated with Cry7Ab4 Toxin

Abstract

Heat shock proteins (HSPs) are essential for the survival and development of animals under various stresses. However, little is known about the function of HSPs in insects response to Bacillus thuringiensis (Bt) toxins treatment. Here, we investigated the role of HSP60 in Myzus persicae (M. persicae) treated with an active Cry7Ab4 toxic core. First, we demonstrated the insensitivity of M. persicae to the Cry7Ab4 toxic core through a membrane capsule method. Then, using protein pull-down assay, several putative Cry7Ab4-binding proteins, including HSP60, were identified in an M. persicae nymph. P-loop GTPase Obg-like ATPase-1 (OLA1) was also found to be a Cry2Ab12-binding protein (unpublished data). Subsequent enzymatic and RT-qPCR assays revealed that highly expressed HSP60 removed the enhanced OLA1 activity caused by Cry7Ab4. ELISA analysis confirmed the binding interactions between Cry7Ab4, HSP60, and OLA1. Interestingly, a combination of ELISA and molecular docking analysis further suggested that HSP60 could block the binding interaction between Cry7Ab4 and OLA1 via higher affinity with Cry7Ab4. Besides, the Jun N-terminal kinase (JNK) pathway was found to be activated. Overall, we proposed the model that HSP60 protects M. persicae from Cry7Ab4 toxin. The study implies that HSP60 can be a crucial factor in insect defense against Cry toxins.