Alkaline phosphatases （ALPs） attached to the midgut membrane with glycosyl phosphotidyl inositol （GPI） have been proposed as the putative CrylAc toxin receptor in Helicoverpa armigera. Activated toxins bind to ALP...Alkaline phosphatases （ALPs） attached to the midgut membrane with glycosyl phosphotidyl inositol （GPI） have been proposed as the putative CrylAc toxin receptor in Helicoverpa armigera. Activated toxins bind to ALP receptors on the brush border membrane vesicle （BBMV） of the midgut epithelium, which activates intracellular oncotic pathways and leads to cell death. However, with the long-term use of Cry toxin, insects can develop a strong resistance to insecticidal delta-endotoxins. Although the molecular mechanism of insect resistance has not been fully understood, insects develop resistance to biopesticides due to changes of toxins binding to midgut receptors. So, it is a good idea to investigate the molecular mechanism of insect resistance by analyzing ALP receptor from Helicoverpa armigera （Ha-ALP）. Based on crystal structure of shrimp alkaline phosphatase, the three-dimensional structure of the CrylAc toxin-binding Ha-ALP receptor was obtained by homology modeling and the model was further evaluated using PROSA energy and ERRAT. The important role of binding of toxin to GalNAc on Ha-ALP was discussed in the aspect of CrylAc toxicity. Specific recognition sites of the binding of oligosaccharides to Ha-ALP were predicted. Post-translational modification of ALP provides insights into the functional properties of ALP and leads to profound understanding of receptor and toxin interactions.展开更多
基金Project supported by the National High Technology Research and Development Program of China （Nos. 2006AA02Z 187, 2006AA 10A212）, the Na- tional Natural Science Foundation of China （Nos. 30670052, 30870064, 30970066） and Ph.D. Programs Foundation of Ministry of Education of China （No. 20060452006）.
文摘Alkaline phosphatases （ALPs） attached to the midgut membrane with glycosyl phosphotidyl inositol （GPI） have been proposed as the putative CrylAc toxin receptor in Helicoverpa armigera. Activated toxins bind to ALP receptors on the brush border membrane vesicle （BBMV） of the midgut epithelium, which activates intracellular oncotic pathways and leads to cell death. However, with the long-term use of Cry toxin, insects can develop a strong resistance to insecticidal delta-endotoxins. Although the molecular mechanism of insect resistance has not been fully understood, insects develop resistance to biopesticides due to changes of toxins binding to midgut receptors. So, it is a good idea to investigate the molecular mechanism of insect resistance by analyzing ALP receptor from Helicoverpa armigera （Ha-ALP）. Based on crystal structure of shrimp alkaline phosphatase, the three-dimensional structure of the CrylAc toxin-binding Ha-ALP receptor was obtained by homology modeling and the model was further evaluated using PROSA energy and ERRAT. The important role of binding of toxin to GalNAc on Ha-ALP was discussed in the aspect of CrylAc toxicity. Specific recognition sites of the binding of oligosaccharides to Ha-ALP were predicted. Post-translational modification of ALP provides insights into the functional properties of ALP and leads to profound understanding of receptor and toxin interactions.
