Applied and Environmental Microbiology (1999) 65, 1900-1903

Victoria Ballester, F. Granero, R.A. de Maagd, D. Bosch, J.L. Ménsua and J. Ferré (1999)
Role of Bacillus thuringiensis toxin domains in toxicity and receptor binding in the diamondback moth
Applied and Environmental Microbiology 65 (5), 1900-1903
Abstract: The toxic fragment of Bacillus thuringiensis crystal proteins consists of three distinct structural domains. There is evidence that domain I is involved in pore formation and that domain II is involved in receptor binding and specificity. It has been found that, in some cases, domain III is also important in determining specificity. Furthermore, involvement of domain III in binding has also been reported recently. To investigate the role of toxin domains in the diamondback moth (Plutella xylostella), we used hybrid toxins with domain III substitutions among Cry1C, Cry1E, and Cry1Ab. Neither Cry1E nor G27 (a hybrid with domains I and II from Cry1E and domain III from Cry1C) was toxic, whereas Cry1C and F26 (the reciprocal hybrid) were equally toxic. H04 (a hybrid with domains I and II from Cry1Ab and domain III from Cry1C) showed toxicity that was of a similar level as that of Cry1Ab and significantly higher than that of Cry1C. Binding assays with ¹²⁵I-Cry1C showed that Cry1C and F26 competed for the same binding sites on midgut membrane vesicles, whereas Cry1E, G27, and H04 did not bind to these sites. Our results show that, in contrast to findings in other insects for the toxins and hybrids used here, toxin specificity as well as specificity of binding to membrane vesicles in the diamondback moth is mediated by domain II (and/or I) and not by domain III.
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Database assignments for author(s): Ruud A. de Maagd, Juan Ferre

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
molecular biology - genes

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Plutella xylostella
Bacillus thuringiensis Cry1A-toxin (entomopathogen)	Plutella xylostella
Bacillus thuringiensis Cry1C-toxin (entomopathogen)	Plutella xylostella