Analysis of amylase and glucosidase as receptors for Bacillus thuringiensis Cry11Ba in mosquito Anopheles gambiae

Bacillus thuringiensis subsp. Jegathesan produces Cry11Ba crystal protein with high toxic to mosquito larvae.  The Cry11Ba toxicity was  dependent on its receptors on mosquitolarval midgut epithelial cells. Previously, a cadherin-like protein (AgCad2), aminopeptidase (AgAPN2) and alkaline phosphatase (AgALP1) were reported to be involved in regulation of  Cry11Ba toxicity on  Anopheles. gambiae larvae.  Here, the cDNAs encoding an α-amylase (AgAmy1) and α-glucosidase (Agm3) were cloned from gambiae larvae midgut. Both were glycophosphatidylinositol (GPI) anchored proteins on brush border membrane (BBMV).  Immunohistochemistry revealed their localization  on different regions of the larval midgut.  AgAmy1 and Agm3 bound Cry11Ba with high affinity, 37.6 nM and 21.1 nM respectively.   Cry11Ba toxicity against A. gambiae larvae was neutralized by both AgAmy1 and Agm3. The results provide evidence that both AgAmy1 and Agm3 function as receptors of Cry11Ba in A. gambiae.