Abstract
Bacillus thuringiensis var. israelensis produces 130-kDa proteins which are toxic to mosquito larvae. The ISRH4 gene encoding 1, 180 a mi no acids of the 130-kDa insecticidal protein was fused with lacZ' on a plasmid, pUC19, and sequentially deleted from the C-terminus to construct a series of deletion mutants. All the deletion mutant genes directed the production of truncated ISRH4 proteins fused with the α-complementing fragment of β-galactosidase in Escherichia coli cells in the presence of isopropyl β-D-thiogaIactopyranoside. Analysis of the mosquito larvicidal activity of deletion mutant proteins revealed that the N-terminal 29 amino acids and the C-terminal 485 amino acids could be removed without loss of the activity.
