This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Masson, L Articles by Brousseau, R Search for Related Content PubMed PubMed Citation Articles by Masson, L Articles by Brousseau, R Agricola Articles by Masson, L Articles by Brousseau, R

 Previous Article  |  Next Article 

Appl Environ Microbiol. 1992 February; 58(2): 642-646

Insecticidal properties of a crystal protein gene product isolated from Bacillus thuringiensis subsp. kenyae.

Biotechnology Research Institute, National Research Council of Canada, Montreal, Quebec.

ABSTRACT

A protoxin gene, localized to a high-molecular-weight plasmid from Bacillus thuringiensis subsp. kenyae, was cloned on a 19-kb BamHI DNA fragment into Escherichia coli. Characterization of the gene revealed it to be a member of the CryIE toxin subclass which has been reported to be as toxic as the CryIC subclass to larvae from Spodoptera exigua in assays with crude E. coli extracts. To directly test the purified recombinant gene product, the gene was subcloned as a 4.8-kb fragment into an expression vector resulting in the overexpression of a 134-kDa protein in the form of phase-bright inclusions in E. coli. Treatment of solubilized inclusion bodies with either trypsin or gut juice from the silkworm Bombyx mori resulted in the appearance of a protease-resistant 65-kDa protein. In force-feeding bioassays, the purified activated protein was highly toxic to larvae of B. mori but not to larvae of Choristoneura fumiferana. In diet bioassays with larvae from S. exigua, the purified protoxin was nontoxic. However, prior activation of the protoxin by tryptic digestion resulted in the appearance of some toxic activity. These results demonstrate that this new subclass of protein toxin may not be useful for the control of Spodoptera species as previously reported. Hierarchical clustering of the nine known lepidopteran-specific CryI toxin subclasses through multiple sequence alignment suggests that the toxins fall into four possible subgroups or clusters.

This article has been cited by other articles:

• Letowski, J., Bravo, A., Brousseau, R., Masson, L. (2005). Assessment of cry1 Gene Contents of Bacillus thuringiensis Strains by Use of DNA Microarrays. Appl. Environ. Microbiol. 71: 5391-5398 [Abstract] [Full Text]