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Binding of Bacillus thuringiensis Cry1Ac toxin to Manduca sexta aminopeptidase‐N receptor is not directly related to toxicity
Author(s) -
Jenkins Jeremy L.,
Lee Mi Kyong,
Sangadala Sreedhara,
Adang Michael J.,
Dean Donald H.
Publication year - 1999
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(99)01559-8
Subject(s) - manduca sexta , aminopeptidase , bacillus thuringiensis , brush border , manduca , cry1ac , biology , biochemistry , binding site , toxin , toxicity , microbiology and biotechnology , vesicle , chemistry , membrane , bacteria , amino acid , insect , transgene , ecology , genetically modified crops , leucine , genetics , organic chemistry , gene
Bacillus thuringiensis Cry1Ac δ‐endotoxin specifically binds a 115‐kDa aminopeptidase‐N purified from Manduca sexta midgut. Cry1Ac domain III mutations were constructed around a putative sugar‐binding pocket and binding to purified aminopeptidase‐N and brush border membrane vesicles (BBMV) was compared to toxicity. Q509A, R511A, Y513A, and 509–511 (QNR‐AAA) eliminated aminopeptidase‐N binding and reduced binding to BBMV. However, toxicity decreased no more than two‐fold, indicating activity is not directly correlated with aminopeptidase‐N binding. Analysis of toxin binding to aminopeptidase‐N in M. sexta is therefore insufficient for predicting toxicity. Mutants retained binding, however, to another BBMV site, suggesting alternative receptors may compensate in vivo.