Identifying the Epitopes of Bacillus thuringiensis Cry2Aa Toxin Involved in Cadherin Interaction by a Monoclonal Antibody.
Appl Biochem Biotechnol
; 195(4): 2709-2718, 2023 Apr.
Article
in En
| MEDLINE
| ID: mdl-36074237
ABSTRACT
Antibodies are a useful tool for assistance to map the binding epitopes in Bacillus thuringiensis Cry toxins and their receptors, and even determine how receptors promote toxicity. In this work, a monoclonal antibody (mAb-1D2) was produced by the hybridoma cell line raised against Cry2Aa toxins, with a half inhibition concentration (IC50) of 9.16 µg/mL. The affinity constant of two recombinant toxin-binding fragments derived from Helicoverpa armigera and Plutella xylostella cadherin-like protein (HaCad-TBR or PxCad-TBR) to Cry2Aa toxin was measured to be 1.21 µM and 1.24 µM, respectively. Competitive ELISA showed that mAb-1D2 competed with HaCad-TBR or PxCad-TBR binding to Cry2Aa. Meanwhile, the toxicity of the Cry2Aa toxin to the H. armigera and P. xylostella larvae were greatly reduced when the toxin was mixed with mAb-1D2, which indicated that cadherin may play an important functional role in the toxicity of Cry2Aa. After transforming mAb-1D2 to a single-chain variable fragment (scFv), the hot spot residues of Cry2Aa with 1D2-scFv, PxCad-TBR, and HaCad-TBR were analyzed by molecular docking. It was demonstrated that the hot spot residues of Cry2Aa involving with 1D2-scFv interaction were mainly in Domain II, and some residues in Domain I. Moreover, mAb-1D2 and the two cadherin fragments shared the common hot spot residues on Cry2Aa, which could explain mAb-1D2 inhibited Cry2Aa binding with cadherin fragments. This monoclonal antibody could be a useful tool for identifying the binding epitopes between Cry2Aa and cadherin, and even assist to analyze the roles of cadherin in Cry2Aa toxicity.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Bacillus thuringiensis
/
Moths
Type of study:
Prognostic_studies
Limits:
Animals
Language:
En
Journal:
Appl Biochem Biotechnol
Year:
2023
Document type:
Article
Affiliation country:
China