Expression of three genes coding for 135-kilodalton entomocidal proteins inBacillus thuringiensis kurstaki |
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Authors: | Dr T Yamamoto A Ehmann J M González Jr B C Carlton |
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Institution: | (1) Agricultural Products Department, duPont Company, Bldg. 402, Experimental St., 19898 Wilmington, Delaware, USA;(2) Shell Development Company, Modesto, California;(3) Department of Molecular and Population Genetics, University of Georgia, Athens, Georgia, USA;(4) Present address: Ecogen, Inc., 19047 Langhorne, PA, USA |
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Abstract: | The HD-1 strain ofBacillus thuringiensis (B.t.)kurstaki contains three homologous genes coding for 130–134-kilodalton entomocidal proteins 13]. In the present study, expression levels of these genes in strains of B.t.kurstaki were determined. In attempts to isolate a protein coded by a single gene, a number of variants were derived from strains of B.t.kurstaki, such as HD-263 and HD-1, by plasmid curing. The entomocidal proteins produced by the parental strains and their plasmid-cured variants were isolated by Sephacryl S-300 column chromatography and peptide-mapped by high performance liquid chromatography (HPLC). The results indicated that HD-263 produced two distinctive proteins, one identical with the protein of HD-73, which contains only a 6.6 kb Hind III class gene, and the other protein presumably coded by a 4.5 kb Hind III class gene. HPLC analysis revealed that 70% of the total protein in the HD-263 crystals consisted of the product of the 6.6 kb gene (6.6-kb protein), and the remaining 30% was the 4.5-kb protein. In the case of HD-1, the crystal consisted of at least two different proteins in equal amounts (50% each). The gene coding for one of these proteins was presumed to be a 5.3 kb Hind III class gene. The remaining 50% of the HD-1 crystal was accounted for by a protein similar to the 4.5-kb protein identified in HD-263. It appeared that the 6.6-kb protein was expressed poorly, if it was indeed expressed, in the HD-1 strain. |
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