Cadherin AdCad1 in Alphitobius diaperinus larvae is a receptor of Cry3Bb toxin from Bacillus thuringiensis.
Bacillus thuringiensis (Bt) Cry proteins are used as components of biopesticides or expressed in transgenic crops to control diverse insect pests worldwide. These Cry toxins bind to receptors on the midgut brush border membrane and kill enterocytes culminating in larval mortality. Cadherin proteins have been identified as Cry toxin receptors in diverse lepidopteran, coleopteran, and dipteran species. In the present work we report a 185 kDa cadherin (AdCad1) from larvae of the lesser mealworm (Alphitobius diaperinus) larvae as the first identified receptor for Cry3Bb toxin. The AdCad1 protein contains typical structural components for Cry toxin receptor cadherins, including nine cadherin repeats (CR9), a membrane-proximal extracellular domain (MPED) and a cytosolic region. Peptides corresponding to the CR9 and MPED regions bound Cry3Bb toxin with high affinities (23 nM and 40 nM) and significantly synergized Cry3Bb toxicity against A. diperinus larvae. Silencing of AdCad1 expression through RNA interference resulted in highly reduced susceptibility to Cry3Bb in A. diperinus larvae. The CR9 peptide fed with toxin to RNAi-treated larvae restored Cry3Bb toxicity. These results are evidences that AdCad1 is a functional receptor of Cry3Bb toxin and that exogenously fed CR9 peptide can overcome the effect of reduced AdCad1expression on Cry3Bb toxicity to larvae.
Department of Entomology, University of Georgia, Athens, GA 30602-2603, USA.
Gang
G
Hua
Department of Entomology, University of Georgia, Athens, GA 30602-2603, USA.
Youngjin
Y
Park
Department of Entomology, University of Georgia, Athens, GA 30602-2603, USA; Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602-2603, USA. Electronic address: mike.adang@gmail.com.
Michael J
MJ
Adang
D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000378:metabolism* / Q000494:pharmacology; D015820:Cadherins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D003001:Cloning, Molecular; D004731:Endotoxins / Q000378:metabolism* / Q000494:pharmacology; D006460:Hemolysin Proteins / Q000378:metabolism* / Q000494:pharmacology; D019476:Insect Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D007814:Larva / Q000187:drug effects / Q000378:metabolism; D010572:Pest Control, Biological; D034622:RNA Interference; D013712:Tenebrio / Q000187:drug effects / Q000378:metabolism*
D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D015820:Cadherins; D004731:Endotoxins; D006460:Hemolysin Proteins; D019476:Insect Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis
Alphitobius diaperinus; Bacillus thuringiensis (Bt); Cadherin; Cry3Bb; dsRNA