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Luminal proteinases from Plodia interpunctella and the hydrolysis of Bacillus thuringiensis CryIA(c) protoxin
- Oppert, B., Kramer, K.J., Johnson, D., Upton, S.J., McGaughey, W.H.
- Insect biochemistry and molecular biology 1996 v.26 no.6 pp. 571
- Plodia interpunctella, larvae, digestive tract, proteinases, Bacillus thuringiensis subsp. entomocidus, Bacillus thuringiensis subsp. kurstaki, bacterial toxins, crystal proteins, insecticide resistance, hydrolysis, enzyme activity, strain differences, proteinase inhibitors, immunochemistry, biological resistance
- The ability of proteinases in gut extracts of the Indianmeal moth, Plodia interpunctella, to hydrolyze Bacillus thuringiensis (Bt) protoxin, casein, and p-nitroanilide substrates was investigated. A polyclonal antiserum to protoxin CryIA(c) was used in Western blots to demonstrate slower protoxin processing by gut enzymes from Bt subspecies entomocidus-resistant larvae than enzymes from susceptible or kurstaki-resistant strains. Enzymes from all three strains hydrolyzed N-alpha-benzoyl-L-arginine p-nitroanilide, N-succinyl-ala-ala-pro-phenylalanine p-nitroanilide, and N-succinyl-ala-ala-pro-leucine p-nitroanilide. Zymograms and activity blots were used to estimate the apparent molecular masses, number of enzymes, and relative activities in each strain. Several serine proteinase inhibitors reduced gut enzyme activities, with two soybean trypsin inhibitors, two potato inhibitors, and chymostatin the most effective in preventing protoxin hydrolysis.