Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Pest Management Science 2240-2246 P20 helper protein Cry2Aa toxin larvicidal activity improvement protection against excessive proteolysis 2016 fdi:010068318 ENG Pest Management Science 1526-498X ISI:000386927800006 12 10.1002/ps.4261 https://www.documentation.ird.fr/hor/fdi:010068318 https://www.documentation.ird.fr/intranet/publi/2016/11/010068318.pdf 72 Horizon (IRD) BACKGROUNDBacillus thuringiensis -endotoxins are the most widely used biopesticides for controlling economically important crop pests and disease vectors. Improving their efficacy is of great benefit. Here, an improvement in Cry2Aa-endotoxin toxicity was attempted via a cry gene over expression system using P20 from B. thuringiensis israelensis. RESULTSThe coexpression of Cry2Aa with P20 resulted in a seven fold increase in its production yield in B. thuringiensis. Generated crystals proved to be significantly more toxic (505.207 mu gg(-1), 1.99mgL(-1) and 1.49mgL(-1)) than the P20-lacking control (720.78 mu gg(-1), 705.69mgL(-1) and 508.51mgL(-1)) against Ephestia kuehniella, Aedes aegypti and Culex pipiens larvae respectively. In vitro, processing experiments revealed a P20-mediated protection of Cry2Aa against degradation under larval gut conditions. Thus, P20 could promote the maintenance of a tightly packaged conformation of Cry2Aa toxins in the larval midgut upon correct activation and binding to its membrane receptors. CONCLUSIONBased on their resistance against excessive proteolysis, Cry2Aa-endotoxins, produced in the presence of P20, could be considered as a successful control agent for E. kuehniella and an effective alternative for mosquito control, implying its possible exploitation in pest management programmes. 052 ; 076 ; 020 ; 084 UR224 Tunisie