Cadherin, Alkaline Phosphatase, and Aminopeptidase N as Receptors of Cry11Ba Toxin from Bacillus thuringiensis subsp. jegathesan in Aedes aegypti

Abstract

Cry11Ba is one of the most toxic proteins to mosquito larvae produced by Bacillus thuringiensis. It binds Aedes aegypti brush border membrane vesicles (BBMV) with high affinity, showing an apparent dissociation constant (K d ) of 8.2 nM. We previously reported that an anticadherin antibody competes with Cry11Ba binding to BBMV, suggesting a possible role of cadherin as a toxin receptor. Here we provide evidence of specific cadherin repeat regions involved in this interaction. Using cadherin fragments as competitors, a C-terminal fragment which contains cadherin repeat 7 (CR7) to CR11 competed with Cry11Ba binding to BBMV. This binding was also efficiently competed by the CR9, CR10, and CR11 peptide fragments. Moreover, we show CR11 to be an important region of interaction with Cry11Ba toxin. An alkaline phosphatase (AaeALP1) and an aminopeptidase-N (AaeAPN1) also competed with Cry11Ba binding to Ae. aegypti BBMV. Finally, we found that Cry11Ba and Cry4Ba share binding sites. Synthetic peptides corresponding to loops ␣8, ␤2-␤3 (loop 1), ␤8-␤9, and ␤10-␤11 (loop 3) of Cry4Ba compete with Cry11Ba binding to BBMV, suggesting Cry11Ba and Cry4Ba have common sites involved in binding Ae. aegypti BBMV. The data suggest that three different Ae. aegypti midgut proteins, i.e., cadherin, AaeALP1, and AaeAPN1, are involved in Cry11Ba binding to Ae. aegypti midgut brush border membranes.

Sodium Solute Symporter and Cadherin Proteins Act as Bacillus thuringiensis Cry3Ba Toxin Functional Receptors in Tribolium castaneum

“…In mosquito larvae, homologous APN, CAD-like, and alkaline phosphatase proteins have been described as Cry11 and Cry4 receptor proteins (6), and in Coleoptera a cadherin-like protein has been demonstrated to act as a Cry3Aa receptor (7). In coleopteran insects, other molecules, such as an ADAM-like metalloprotease (8) and alkaline phosphatase (9), have been proposed as putative Cry receptors.…”

Aedes aegypti Membrane-Bound Alkaline Phosphatase Expressed in Escherichia coli Retains High-Affinity Binding for Bacillus thuringiensis Cry4Ba Toxin

“…Of particular interest, ALPs (EC 3.1.3.1; phosphomonoester hydrolases), ubiquitous enzymes widely found in microorganisms and animal kingdoms, are a highly conserved family of largely distributed cell surface and secreted metalloenzymes; many are GPI-anchored glycoproteins (for a review, see reference 13). To date, various ALPs from mosquitoes and other insect species have been reported as functional Cry toxin receptors, including Cry11Aa receptors from A. aegypti (8,9), Cry11Ba receptors from A. aegypti (12) and Anopheles gambiae (10), a Cry1Ab receptor from Manduca sexta (3), and Cry1Ac receptors from Helicoverpa armigera (14) and Heliothis virescens (17).…”

Using the Bio-Insecticide Bacillus Thuringiensis Israelensis in Mosquito Control

“…Alternative splicing of the receptor gene due to transposable elements was shown to confer resistance to Bacillus sphaericus binary toxins in Culex pipiens populations (Darboux et al, 2007) but such mechanism has not been demonstrated so far for Bti toxins. Cross-resistance mechanisms between different Cry toxins have been reported, presumably involving shared membrane receptors (Siqueira et al, 2004;Zhao et al, 2001;Xu et al, 2010;Likitvivatanavong et al, 2011). In lepidopterans, four types of receptors for Cry1A have been identified: cadherin, glycosylphosphatidylinosytol (GPI)-anchored APN (aminopeptidase N), GPI-anchored ALP (alkaline phosphatase) and glycolipids (reviewed in Pigott & Ellar, 2007).…”