title: A 104 kDa Aedes aegypti aminopeptidase N is a putative receptor for the Cry11Aa toxin from Bacillus thuringiensis subsp. israelensis.
abstract: The Cry11Aa protein produced in Bacillus thuringiensis subsp. israelensis, a bacterial strain used worldwide for the control of Aedes aegypti larvae, binds midgut brush border membrane vesicles (BBMV) with an apparent K(d) of 29.8 nM. Previously an aminopeptidase N (APN), named AaeAPN2, was identified as a putative Cry11Aa toxin binding protein by pull-down assays using biotinylated Cry11Aa toxin (Chen et al., 2009. Insect Biochem. Mol. Biol. 39, 688-696). Here we show this protein localizes to the apical membrane of epithelial cells in proximal and distal regions of larval caeca. The AaeAPN2 protein binds Cry11Aa with high affinity, 8.6 nM. The full-length and fragments of AaeAPN2 were cloned and expressed in Escherichia coli. The toxin-binding region was identified and further competitive assays demonstrated that Cry11Aa binding to BBMV was efficiently competed by the full-length AaeAPN2 and the fragments of AaeAPN2b and AaeAPN2e. In bioassays against Ae. aegypti larvae, the presence of full-length and a partial fragment (AaeAPN2b) of AaeAPN2 enhanced Cry11Aa larval mortality. Taken together, we conclude that AaeAPN2 is a binding protein and plays a role in Cry11Aa toxicity.
authors.affiliation: Department of Cell Biology and Neuroscience, University of California, Riverside, CA 92521, USA.
authors.forename: Jianwu
authors.initials: J
authors.lastname: Chen
authors.forename: Supaporn
authors.initials: S
authors.lastname: Likitvivatanavong
authors.forename: Karlygash G
authors.initials: KG
authors.lastname: Aimanova
authors.forename: Sarjeet S
authors.initials: SS
authors.lastname: Gill
mesh_terms: D000330:Aedes / Q000201:enzymology*; D000595:Amino Acid Sequence; D000818:Animals; D001413:Bacillus thuringiensis / Q000378:metabolism / Q000472:pathogenicity; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000378:metabolism*; D018826:CD13 Antigens / Q000378:metabolism*; D004064:Digestive System; D004731:Endotoxins / Q000378:metabolism*; D006460:Hemolysin Proteins / Q000378:metabolism*; D007814:Larva
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis; D018826:CD13 Antigens
keywords: Aedes aegypti; Aminopeptidase; Bacillus thuringiensis; Binding affinity; Cry11Aa toxin; Midgut; Receptor