Bacillus thuringiensis Cry1Ab Domain III beta-16 Is Involved in Binding to Prohibitin, Which Correlates with Toxicity against Helicoverpa armigera (Lepidoptera: Noctuidae)

Author(s)

Sena da Silva, Igor Henrique ^[1] ; Gomez, Isabel ^[2] ; Pacheco, Sabino ^[2] ; Sanchez, Jorge ^[2] ; Zhang, Jie ^[3] ; Luque Castellane, Tereza Cristina ^[4] ; Desiderio, Janete Aparecida ^[4] ; Soberon, Mario ^[2] ; Bravo, Alejandra ^[2] ; Polanczyk, Ricardo Antonio ^[1]

Affiliation

^[1] Sao Paulo State Univ Unesp, Sch Agr & Vet Sci, Dept Agr Prod Sci, Sao Paulo - Brazil

^[2] Univ Nacl Autonoma Mexico, Inst Biotecnol, Dept Mol Microbiol, Cuernavaca, Morelos - Mexico

^[3] Chinese Acad Agr Sci, Inst Plant Protect, State Key Lab Biol Plant Dis & Insect Pests, Beijing - Peoples R China

^[4] Sao Paulo State Univ Unesp, Sch Agr & Vet Sci, Dept Appl Biol Farming, Sao Paulo - Brazil

• Document type: Journal article
• Source: Applied and Environmental Microbiology; v. 87, n. 2 JAN 2021.
• Web of Science Citations: 1

Abstract

Helicoverpa armigera is a major insect pest of several crops worldwide. This insect is susceptible to some Bacillus thuringiensis (Bt) Cry insecticidal proteins expressed in transgenic crops or used in biopesticides. Previously, we identified H. armigera prohibitin (HaPHB) as a Cry1Ac-binding protein. Here, we further analyzed the potential role of PHB as a Cry toxin receptor in comparison to cadherin (CAD), well recognized as a Cry1Ac receptor. HaPHB-2 midgut protein and HaCAD toxin-binding region (TBR) fragment from H. armigera were expressed in Escherichia coli cells, and binding assays with different Cry1 toxins were performed. We demonstrated that Cry1Ab, Cry1Ac, and Cry1Fa toxins bound to HaPHB-2 in a manner similar to that seen with HaCAD-TBR. Different Cry1Ab mutant toxins located in domain II (Cry1AbF371A and Cry1AbG439D) or domain III (Cry1AbL511A and Cry1AbN514A), which were previously characterized and found to be affected in receptor binding, were analyzed regarding their binding interaction with HaPHB-2 and toxicity against H. armigera. One beta-16 mutant (Cry1AbN514A) showed increased binding to HaPHB-2 that correlated with 6-fold-higher toxicity against H. armigera, whereas the other beta-16 mutant (Cry1AbL511A) was affected in binding to HaPHB-2 and lost toxicity against H. armigera. Our data indicate that beta-16 from domain III of Cry1Ab is involved in interactions with HaPHB-2 and in toxicity. This report identifies a region of Cry1Ab involved in binding to HaPHB-2 from a Lepidoptera insect, suggesting that this protein may participate as a novel receptor in the mechanism of action of the Cry1 toxins in H. armigera. IMPORTANCE Helicoverpa armigera is a polyphagous pest that feeds on important crops worldwide. This insect pest is sensitive to different Cry1 toxins from Bacillus thuringiensis. In this study, we analyzed the potential role of PHB-2 as a Cry1 toxin receptor in comparison to CAD. We show that different Cry1 toxins bound to HaPHB-2 and HaCAD-TBR similarly and identify beta-16 from domain III of Cry1Ab as a binding region involved in the interaction with HaPHB-2 and in toxicity. This report characterized HaPHB-Cry1 binding interaction, providing novel insights into potential target sites for improving Cry1 toxicity against H. armigera. (AU)

• FAPESP's process: 19/00264-4 - Mechanism of action of Cry1Ac toxin from Bacillus thuringiensis in Helicoverpa armigera (Lepidoptera: Noctuidae)
• Grantee: Igor Henrique Sena da Silva
• Support type: Scholarships abroad - Research Internship - Doctorate
• FAPESP's process: 18/13974-7 - Bacillus thuringiensis Cry1Ac action mechanism on Helicoverpa armigera (Lepidoptera: Noctuidae)
• Grantee: Igor Henrique Sena da Silva
• Support type: Scholarships in Brazil - Doctorate