Possible Insecticidal Mechanism of Cry41-Related Toxin against Myzus persicae by Enhancing Cathepsin B Activity

Abstract

Cry toxins produced by Bacillus thuringiensis are well known for their high insecticidal activities against Lepidoptera, Diptera, and Coleoptera; however, their activities against Aphididae are very low. Recently, it has been reported that a Cry41-related toxin exhibited moderate activity against the aphid Myzus persicae, and thus, it is highly desirable to uncover its unique mechanism. In this paper, we report that Cathepsin B, calcium-transporting ATPase, and symbiotic bacterial-associated protein ATP-dependent-6-phosphofructokinase were pulled down from the homogenate of M. persicae as unique proteins that possibly bound to Cry41related toxin. Cathepsin B has been reported to cleave and inactivate antiapoptotic proteins and plays a role in caspase-initiated apoptotic cascades. In this study, Cathepsin B was expressed in Escherichia coli and purified, and in vitro interaction between recombinant Cathepsin B and Cry41-related toxin was demonstrated. Interestingly, we found that addition of Cry41-related toxin obviously enhanced Cathepsin B activity. We propose a model for the mechanism of Cry41-related toxin as follows: Cry41-related toxin enters the aphid cells and enhances Cathepsin B activity, resulting in acceleration of apoptosis of aphid cells.

Protection of HSP60 in Myzus persicae Treated with Cry7Ab4 Toxin

“…To identify Cry7Ab4-binding proteins in M. persicae, pull-down and liquid chromatography tandem mass spectrometry (LC–MS/MS) assays were carried out as described previously. , In brief, 1 mL of active Cry7Ab4 toxic core (0.5 mg/mL) was incubated with a pre-equilibrated Sepharose 4B beads (0.5 mol/L NaCl, 0.1 mol/L NaHCO 3 , pH 8.3) (GE Healthcare, USA) at 4 °C for 12 h. Subsequently, 25 μL of Cry7Ab4-coupled Sepharose 4B matrix was incubated with 50 μL of M. persicae homogenate (200 fourth instar M.…”

“…The target bands were excised from a silver-stained gel and identified by LC–MS/MS (BGI Genomics, Shenzhen, China). LC–MS/MS data were searched as described previously …”

“…To identify Cry7Ab4binding proteins in M. persicae, pull-down and liquid chromatography tandem mass spectrometry (LC−MS/MS) assays were carried out as described previously. 28,29 In brief, 1 mL of active Cry7Ab4 toxic core (0.5 mg/mL) was incubated with a pre-equilibrated Sepharose 4B beads (0.5 mol/L NaCl, 0.1 mol/L NaHCO 3 , pH 8.3) (GE Healthcare, USA) at 4 °C for 12 h. Subsequently, 25 μL of Cry7Ab4-coupled Sepharose 4B matrix was incubated with 50 μL of M. persicae homogenate (200 fourth instar M. persicae nymphs were thoroughly ground in 500 μL of PBS buffer) at 4 °C for 1 h. Next, Cry7Ab4-binding proteins were resolved on 12% sodium dodecyl sulfate−polyacrylamide gel electrophoresis (SDS-PAGE), followed by staining using a Fast Silver Stain Kit (Beyotime Biotech, Jiangsu, China). Three biological replicates were performed.…”

A possible mechanism of Cry7Ab4 protein in delaying pupation of Plutella xylostella larvae

“…Our previous work has identified proteins from midgut juice that bind to Cry toxins, and these non-receptor proteins also affect insecticidal activities of Cry toxins ( 16 – 18 ). It has been reported that Cry toxin receptors in P. xylostella , including ALP and ABCC, are regulated by the MAPK signal pathway, and a high level of hormones promotes the expression of ALP and ABCC by activating the MAPK pathway, leading to Cry resistance ( 19 ).…”

Indications for the potential of Cry1Ab1 for inhibiting aphid development and virus transmission

“…2005) were reported to be Cry1Ab1-binding proteins in the midgut juice of Plutella xylostella, and Peroxidase-C was a Cry1Ab-binding protein in Spodoptera exigua (Lu et al 2017). Zhao et al found that Cry41-realted interacted with Cathepsin B and enhanced its activity, causing acceleration of apoptosis of aphid cells (Zhao et al 2020). Additionally, galectin-14 was reported to compete with Cry11Aa for binding to BBMVs and ALP1 in Aedes aegypti to prevent effective binding of the toxin to receptors (Zhang et al 2018).…”