SciELO - Scientific Electronic Library Online

vol.90 issue1Mechanism of action of Bacillus thuringiensis toxinsBiochemistry and mode of action of the Bacillus sphaericus toxins author indexsubject indexarticles search
Home Pagealphabetic serial listing  

Services on Demand




Related links


Memórias do Instituto Oswaldo Cruz

Print version ISSN 0074-0276On-line version ISSN 1678-8060

Mem. Inst. Oswaldo Cruz vol.90 no.1 Rio de Janeiro Jan./Feb. 1995 

Exploration of receptor binding of Bacillus thuringiensis toxins

In-Seok Kwak1 

Hong Lu1 

Donald H Dean1 

Ohio State University, The Department of Biochemistry, Columbus, USA


Wild type and mutant toxins of Bacillus thuringiensis delta-endotoxins were examined for their binding to midgut brush border membrane vesicles (BBMV). CryIAa, CryIAb, and CryIAc were examined for their binding to Gypsy moth (Lymantria dispar) BBMV. The binding of CryIAa and CryIAc was directly correlated with their toxicity, while CryIAb was observed to have lower binding than expected from its toxicity. The latter observation confirms the observation of Wolfersberger (1990). The "rule" of reciprocity of binding and toxicity is apparently obeyed by CryIAa and CryIAc, but broken by CryIAb on L. dispar. Alanine substitutions were made in several positions of the putative loops of CryIAa to test the hypothesis that the loops are intimately involved in binding to the receptor. The mutant toxins showed minor shifts in heterologous binding to Bombyx mori BBMV, but not enough to conclude that the residues chosen play critical roles in receptor binding.

Key words: ion channel toxin; biological insecticide


Creative Commons License All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License