Protease activation of the entomocidal protoxin of Bacillus thuringiensis subsp. kurstaki.

摘要: Two isolates of Bacillus thuringiensis subsp. kurstaki were examined which produced different levels intracellular proteases. Although the crystals from both strains had comparable toxicity, one strains, LB1, a strong polypeptide band at 68,000 molecular weight in protein crystal; other, HD251, no such was evident. When proteases measured, strain HD251 less than 10% proteolytic activity found LB1. These primarily neutral metalloproteases, although low other detected. In synthesis protease increased as cells began to sporulate; however, appeared much later sporulation cycle. The LB1 very high when making crystal toxin, whereas reduced present during toxin synthesis. insecticidal (molecular weight, 68,000) could be prepared by cleaving protoxin 135,000) with trypsin, followed ion-exchange chromatography. procedure described gave quantitative recovery toxic activity, and approximately half total recovered. Calculations show that these results correspond stoichiometric conversion toxin. toxicities whole crystals, soluble protein, purified comparable.