Synergism in mosquitocidal activity of 26 and 65 kDa proteins from Bacillus thuringiensis subsp. israelensis crystal

AbstractThree major protein components, 130, 65 and 26 kDa of solubilized Bacillus thuringiensis subsp. israelensis crystal were separated by gel filtration. The isolated 26 kDa protein is inactive against mosquito larvae at 6.4 μgml protein. The 65 kDa protein is also inactive towards mosquito larvae at low concentrations and shows but weak activity at higher concentrations. However, 26 and 65 kDa proteins simultaneously present at low concentrations exhibit high mosquitocidal activity. Similar synergistic effects are observed between 26 and 130 kDa proteins. These results differ from the findings of other investigators who have reported that a single protein component is sufficient for mosquitocidal activity [(1984) FEBS Lett. 175, 377-382; (1985) Biochem. Biophys. Res. Commun. 126, 961-965]. Our data suggest that the simultaneous presence of at least two proteins is required for activity.SynergismMosquitocidal activityCrystal protei