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Bacillus thuringiensis subspecies morrisoni strain HD12,whose genome harbors multiple insecticidal protein-encoding genes,includes eight cry genes,as indicated by genome sequencing.This strain produces crystals that are toxic to lepidopteran species.These crystal inclusions were purified by sucrose gradients and sodium dodecyl sulphate-polyacrylamide gel electrophoresis(SDS-PAGE),followed by liquid chromatography-mass spectrometry,and found to contain five proteins(Cry1Da,Cry1 Ae,Cry1Bb,Cry1 Fb,and Cry1Ja).The transcriptional activities of the cry1 Da,cry1Ae,cry1 Bb,cry1Fb,and cry1 Ja promoters indicated that transcription of cry1 Da is controlled by SigE;however,the other four cry genes were found to be controlled by both SigE and SigK.The activities of the cry1 Ja and cry1 Fb promoters were the strongest among the five genes studied.These promoters were therefore used to direct the expression of the Cry1Ac- and Cry2Ab-encoding genes concurrently in a single strain.Our findings indicate that promoters with the same transcriptional profile may be used to direct the expression of different cry genes in one strain.Our results are expected to be valuable forthe construction of strains with efficient expression of multiple cry genes in orderto overcome current limitations associated with the application of 6.thuringiensis-based insecticides.
Bacillus thuringiensis subspecies morrisoni strain HD12, whose genome harbors multiple insecticidal protein-encoding genes, includes eight cry genes, as indicated by genome sequencing. This strain produces crystals that are toxic to lepidopteran species. The crystal inclusions were purified by sucrose gradients and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) followed by liquid chromatography-mass spectrometry, and found to contain five proteins (Cry1Da, Cry1 Ae, Cry1Bb, Cry1 Fb, and Cry1Ja) .The transcriptional activities of the cry1 Da, cry1Ae, cry1 Bb, cry1Fb, and cry1 Ja promoters indicated that transcription of cry1 Da is controlled by SigE; however, the other four cry genes were found to be controlled by both SigE and SigK. activities of the cry1 Ja and cry1 Fb promoters were the strongest among the five genes studied. promoters were therefore used to direct the expression of the Cry1Ac- and Cry2Ab-encoding genes concurrently in a single strain. Our findings indica te that promoters with the same transcriptional profile may be used to direct the expression of different cry genes in one strain.Our results are expected to be valuable forthe construction of strains with efficient expression of multiple cry genes in orderto overcome current limitations associated with the application of 6.thuringiensis-based insecticides.