IDENTIFICATION, ISOLATION, AND CLONING OF A BACILLUS-THURINGIENSIS CRYIAC TOXIN-BINDING PROTEIN FROM THE MIDGUT OF THE LEPIDOPTERAN INSECT HELIOTHIS-VIRESCENS

Bacillus thuringiensis toxins are insecticidal to a variety of insect species, The selectivity of the toxins produced by these bacteria is d ependent on both the toxin structure and the receptor sites that are p resent in different insect species, One of these toxins, CryIAc, is hi ghly insecticidal to the noctuid pest Heliothis virescens. Using toxin overlay assay, a 120-kDa glycoprotein was identified as a toxin-bindi ng protein. This protein was partially purified, its N-terminal sequen ce was determined, and the full-length cDNA encoding this protein was isolated from a H. virescens midgut library, The B. thuringiensis toxi n-binding protein, BTBP1, has high homology to aminopeptidase N from e ukaryotes and prokaryotes.