Isolation of the Astacin-like metalloprotease coding gene (astl) and assessment of its insecticidal activity againstSpodoptera littoralisandSitophilus oryzae

Abstract

AbstractAstacin- like metalloprotease (astl) is a multi-domain metallopeptidase that has protease activity against a number of organisms; including fish, frogs, birds and insects. In this present investigation, the full length ofastlcDNA was cloned from spider species,Hasarius adansoni. Sequencing of the clonedastlcDNA proved that its full length including 802 bp with 714bp open reading frame encoding for 238 amino acids. The catalytic domain comprised of 489 nts was cloned and expressed by the yeast expression systemPichia pastorisand its insecticidal activity was determined against two species of agricultural insectsSpodoptera littoralis(Lepidoptera:Noctuidae) andSitophilus oryzae(Coleoptera:Curculionidae). Bioassay was performed using three concentrations (100,500 and 1000 ppm) for four days forS. littoralisand 14 days forS. oryzae.In addition, the astl was fused to the GNA snowdrop lectin in the same frame and expressed inP. pastoris. The synergistic effect of astl and GNA was examined on theS. littoralislarvae andS. oryzaeadults. The mortality percentages of the fused protein (Ha-astl/GNA) “1000 ppm” after 4 days, were 78.6%± 4.16 and 71.66% ±3.51 for first and second spodpotera larval instars, respectively. While, lower mortality of the fused protein of the same concentration was observed onS. oryzaeadults, 49.3±2.08 %.