Helix 4 mutants of the Bacillus thuringiensis insecticidal toxin Cry1Aa display altered pore-forming abilities

Article Abstract:

Studies done to investigate the functional role of alpha4, the pore-forming properties of mutants in which each charged residue (R27, E128, E129, R131 and D136) in alpha 4 was replaced individually with a neutral or an oppositely charged amino acid were examined in brush border membrane vesicles isolated from Manduca sexta by using an osmotic swelling permeability assay are reported. Results reveal that the main effect of the mutations was to decrease the toxin's ability to form pores and the results provide further evidence that alpha-helix 4 plays a significant role in the mechanism of pore formation.

Science & research, Gene mutations, Gene mutation, Microbiological research

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

Article Abstract:

Genetics of the protoxin gene isolated from Bacillus thuringiensis was studied to determine itstoxicity. It was cloned using Escherichia coli as an expression vector which resulted in the overexpression of a 134-kilodaton protein which formed inclusion bodies. The protein gene exhibited toxicity to the insect specie Bombyx mori (silkworm) but not to Choristoneura fumiferana (spruce budworm) or to Spodoptera exigua (beet armyworm).

Physiological aspects, Bacterial toxins, Microbial insecticides

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Assessment of cyr1 gene contents of Bacillus thuringiensis strains by use of DNA microarrays

Article Abstract:

An oligonucleotide-based DNA microarray (cryArray) to test the feasibility of using microarrays to identify the cry gene content of Bacillus thuringiensis strains is designed. Specific 50-mer oligonucleotide probes representing the cry1 primary and tertiary ranks are designed based on multiple cry gene sequence alignments.

Usage, DNA microarrays

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