EFFECTS OF HELPER PROTEINS ENCODED BY p19 AND orf1-orf2 GENES ON CytlAa PROTEIN EXPRESSION IN ACRYSTALLIFEROUS STRAIN OF BACILLUS THURINGIENSIS

摘要

A series of plasmids were constructed to examine the effects of p19 and orf1-orf2 genes from Ba- cillus thuringiensis on CytlAa synthesis and inclusion formation. The plasmids expressed the cytlAa gene along with either p19 or orf1-orf2, or each of them coordinatively with p20 in the acrystalliferous strain of B . thuringiensis subsp. israelensis 4Q7. No effect on the expression of CytlAa protein was found when P19 or Orfl-Orf2 co-expressed with CytlAa. However, when including p20 gene, the constructs with pl9 or orf1-orf2 gene produced lower yield of CytlAa proteins than without pl9 or orf1-orf2 gene. Electron microscopy observation and bioassay showed that P19 and Orf1-Orf2 have no influence on the crystal size and toxicity of CytlAa protein. It is presumed that P19 and Orf1-Orf2 might have negative effects on Cyt1Aa synthesis in B. thuringiensis .