Aminopeptidase-N from the Helicoverpa armigera (Hubner) Brush Border Membrane Vesicles as a Receptor of Bacillus thuringiensis Cry1Ac δ-Endotoxin

摘要

Brush border membrane vesicles (BBMVs) were prepared from the 2 instar larvae of . Binding of the activated Cry1Ac of (Bt) toxin was shown by immunoblot. A 120-kDa protein was identified as a receptor for the Cry1Ac type δ-endotoxin. The aminopeptidase-N activity of BBMVs was measured as the hydrolysis of -leucine -nitroanilide. The specific activity was 35 units/mg protein. The BBMV preparation also showed low level of alkaline phosphatase activity. Zn chelating agents 2,2′-dipyridyl and 1,10-phenanthroline inhibited aminopeptidase activity at 10 m concentration, indicating the presence of zinc-dependent aminopeptidase in the brush border of . The aminopeptidase activity was increased with increasing concentration of δ-endotoxin. The purified 120-kDa binding protein was N-terminally sequenced. The first 10-amino-acid sequence showed 60–77% similarity with human cysteine-rich secretory protein-1 precursor, inhibin alpha chain precursor. Salmonella flagellar hook protein and yeast carboxypeptidase S.