38th Annual Meeting of the Society for Invertebrate Pathology

Binding of Bacillus thuringiensis Cry toxins to susceptible larval midgut receptors results in toxin insertion and pore formation, leading to cell death by osmotic lysis. In this study, attempts were made to isolate and characterize Cry4Ba toxin-binding molecules. The 65-kDa FPLC-purified Cry4Ba mutant (R203Q/S204C) was covalently linked to the activated thiol sepharose 4B via position Cys-204 and used for affinity purification of a specific protein from CHAPS soluble fractions of Aedes aegypti homogenate. Binding interaction was performed in a binding buffer (0.3 M NaCl, 50 mM NaH₂PO₄, pH 8.0) containing 80 mM KI and bound toxin-gut complexes were eluted with the buffer containing 50 mM DTT. SDS-PAGE analysis via Coomassie brilliant blue staining revealed approximately 30-150-kDa larval gut proteins co-eluted with the purified Cry4Ba toxin. Binding specificity of these isolated proteins with the Cry4Ba toxin was confirmed by toxin overlay assays. Further characterization of these toxin bound proteins will be discussed.