| Institution: | 1.Laboratory of Biopesticides, Centre of Biotechnology of Sfax,University of Sfax,Sfax,Tunisia;2.Laboratoire de Microorganismes et de Biomolécules, Centre de Biotechnologie de Sfax,Université de Sfax,Sfax,Tunisia;3.Institut de Recherche pour le Développement (IRD), UMR MIVEGEC (UM1-UM2-CNRS 5290-IRD 224) Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contr?le, Laboratoire de Lutte contre les Insectes Nuisibles (LIN),Montpellier,France;4.Research Group on Molecular and Cellular Screening Processes, Laboratory of Microorganisms and Biomolecules, Centre of Biotechnology of Sfax,Sfax,Tunisia;5.Biological & Environmental Sciences Department, College of Arts and Sciences,Qatar University,Doha,Qatar |
| Abstract: | Attempts have been made to express or to merge different Cry proteins in order to enhance toxic effects against various insects. Cry1A proteins of Bacillus thuringiensis form a typical bipyramidal parasporal crystal and their protoxins contain a highly conserved C-terminal region. A chimerical gene, called cry(4Ba-1Ac), formed by a fusion of the N-terminus part of cry4Ba and the C-terminus part of cry1Ac, was constructed. Its transformation to an acrystalliferous B. thuringiensis strain showed that it was expressed as a chimerical protein of 116 kDa, assembled in spherical to amorphous parasporal crystals. The chimerical gene cry(4Ba-1Ac) was introduced in a B. thuringiensis kurstaki strain. In the generated crystals of the recombinant strain, the presence of Cry(4Ba-1Ac) was evidenced by MALDI-TOF. The recombinant strain showed an important increase of the toxicity against Culex pipiens larvae (LC50 = 0.84 mg l?1 ± 0.08) compared to the wild type strain through the synergistic activity of Cry2Aa with Cry(4Ba-1Ac). The enhancement of toxicity of B. thuringiensis kurstaki expressing Cry(4Ba-1Ac) compared to that expressing the native toxin Cry4Ba, might be related to its a typical crystallization properties. The developed fusion protein could serve as a potent toxin against different pests of mosquitoes and major crop plants. |
