Bacillus thuringiensis ssp. galleriae simultaneously produces two δ-endotoxins differing strongly in primary structure and entomocidal activity

AbstractStrain 11–67 of B. thuringiensis ssp. galleriae produces two entomocidal proteins of molecular mass 130 kDa. Limited proteolysis of these proteins — protoxins — yields the ‘true’ toxins of molecular mass 65 kDa which are drastically different with respect to their charges at pH 8.6, immunological properties and toxicity (host range). One of the proteins — the ‘negative’ component — is toxic for Lymantria dispar larvae and shows 65% homology when compared with B. thuringiensis ssp. kurstaki δ-endotoxins. The other — the ‘positive’ component — is toxic for Galleria mellonella larvae. Its N-terminal sequence of 11 amino acid residues is homologous with the B. thuringiensis ssp. israelensis and san diego endotoxins known to be toxic for Coleoptera and Diptera but not for Lepidoptera. Hence, B. thuringiensis subspecies may produce simultaneously δ-endotoxins differing substantially in structural features and host range

Nucleotide sequence of a novel δ-endotoxin gene cryIg of Bacillus thuringiensis ssp. galleriae

AbstractA gene cryIg coding for entomocidal protein δ-endotoxin of Bacillus thuringiensis ssp. galleriae str. 11-67 named CryIG has been cloned and sequenced (EMBL accession number X58120). The deduced amino acid sequence that contains 1156 amino acid residues shows only 28% of identical residues, when compared with other δ-endotoxins of the CryI family. The extent of identity is substantially higher for some regions of the sequence (‘conserved blocks’), that presumably bear important structural or functional properties. This implies that CryIG δ-endotoxin follows the same type of polypeptide chain folding as other Cryl proteins, whereas peculiarities of primary structure help to explain its unique specificity