title: Mutations at the arginine residues in alpha8 loop of Bacillus thuringiensis delta-endotoxin Cry1Ac affect toxicity and binding to Manduca sexta and Lymantria dispar aminopeptidase N.
abstract: The functional role of the alpha8 loop residues in domain II of Bacillus thuringiensis Cry1Ac toxin was examined. Alanine substitution mutations were introduced in the residues from 275 to 293. Among the mutant toxins, substitutions at R281 and R289 affected toxicity to Manduca sexta and Lymantria dispar. Loss of toxicity by these mutant toxins was well correlated with reductions in binding affinity for brush border membrane vesicles and the purified receptor, aminopeptidase N (APN), from both insects. These data suggest that the two arginine residues in the alpha8 loop region are important in toxicity and APN binding in L. dispar and M. sexta.
authors.affiliation: Department of Biochemistry, The Ohio State University, Columbus, OH 43210, USA.
authors.forename: M K
authors.initials: MK
authors.lastname: Lee
authors.forename: J L
authors.initials: JL
authors.lastname: Jenkins
authors.forename: T H
authors.initials: TH
authors.lastname: You
authors.forename: A
authors.initials: A
authors.lastname: Curtiss
authors.forename: J J
authors.initials: JJ
authors.lastname: Son
authors.forename: M J
authors.initials: MJ
authors.lastname: Adang
authors.forename: D H
authors.initials: DH
authors.lastname: Dean
mesh_terms: D019943:Amino Acid Substitution; D000626:Aminopeptidases / Q000378:metabolism*; D000818:Animals; D001413:Bacillus thuringiensis; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D001427:Bacterial Toxins; D001667:Binding, Competitive / Q000187:drug effects; D001681:Biological Assay; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D004064:Digestive System / Q000737:chemistry; D004731:Endotoxins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D006460:Hemolysin Proteins; D019476:Insect Proteins / Q000378:metabolism*; D007814:Larva; D007915:Lepidoptera; D018402:Manduca; D008871:Microvilli / Q000378:metabolism; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D010572:Pest Control, Biological; D011485:Protein Binding; D017434:Protein Structure, Tertiary / Q000502:physiology; D013329:Structure-Activity Relationship; D020349:Surface Plasmon Resonance
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; D019476:Insect Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis; D000626:Aminopeptidases