title: Construction of a Bacillus thuringiensis genetically-engineered strain harbouring the secreted Cry1Ia delta-endotoxin in its crystal.
abstract: Unlike other Bacillus thuringiensis Cry proteins, Cry1Ia does not form a crystal since it is a secreted delta-endotoxin. We have engineered a Cry1Iac chimeric protein by substituting the C-terminal part of Cry1Ia by the corresponding Cry1Ac part. When expressed in an acrystalliferous B. thuringiensis strain, Cry1Iac did not crystallize, but when expressed in the crystalliferous strain BNS3, the chimeric protein co-crystallized with the endogenous Cry1A delta-endotoxins forming a typical bipyramidal crystal. The integration of Cry1Ia in the composition of the crystal of BNS3 led to an increase of its delta-endotoxin production (13%) and to an improvement (60%) of its toxicity against Agrotis ipsilon.
authors.affiliation: Biopesticides Team, Centre of Biotechnology of Sfax, University of Sfax, P.O. Box 1177, 3061 Sfax, Tunisia. dammak_mar@yahoo.fr
authors.forename: Mariam
authors.initials: M
authors.lastname: Dammak
authors.forename: Samir
authors.initials: S
authors.lastname: Jaoua
authors.forename: Slim
authors.initials: S
authors.lastname: Tounsi
mesh_terms: D001413:Bacillus thuringiensis / Q000502:physiology*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D003001:Cloning, Molecular / Q000379:methods*; D004731:Endotoxins / Q000096:biosynthesis* / Q000235:genetics; D024861:Genetic Enhancement / Q000379:methods*; D006460:Hemolysin Proteins / Q000096:biosynthesis* / Q000235:genetics; D015202:Protein Engineering / Q000379:methods*
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis