cDNA cloning and expression of Bacillus thuringiensis Cry1Aa toxin binding120 kDa amninopeptidase N from Bombyx mori

Bacillus thuringiensis Cry1Aa toxin binds to a 120 kDa putative receptor pr otein in the Bombyx mori midgut. Recently, this protein was purified and id entified as glycosyl-phosphatidylinositol (GPI) anchored aminopeptidase N ( APN). In this study, a full-length cDNA thought to encode this 120 kDa APN was isolated and sequenced. It has a 2958 bp ORF encoding 986 amino acids. In the deduced amino acid sequence, we identified GPI-anchor and zinc-metal lopeptidase signals, which are the same as those of APNs of other insects t hat are reported to be putative Cry1 toxin receptors. The B. mori APN amino acid sequence also has a high similarity with those of the other APNs. Sub sequently, the recombinant APN was expressed by Escherichia coli and its Cr y1Aa toxin binding ability was analyzed. Ligand blotting showed that Cry1Aa toxin bound to the recombinant APN. (C) 1999 Elsevier Science B.V. All rig hts reserved.