苏云金杆菌辅助蛋白基因p19和orf1-orf2对杀虫晶体蛋白Cyt1 Aa表达的影响(英文)

为检测苏云金杆菌辅助蛋白P19和ORF1 ORF2对杀虫晶体蛋白Cyt1Aa表达的影响 ,构建了 5个重组表达质粒。 5个质粒都含有cyt1Aa基因 ,但pT1只含有cyt1Aa基因 ,pT2同时含有p19基因 ,pT3同时含有orf1 orf2串联基因 ,pT4同时含有p19基因和p2 0基因 ,pT5同时含有orf1 orf2串联基因和p2 0基因。将这 5个表达质粒和质粒pWF4 5电转化到苏云金杆菌晶体缺陷型 4Q7中 ,分别获得转化菌株Bt T1、Bt T2、Bt T3、Bt T4、Bt T5和Bt WF4 5。SDS PAGE结果显示 ,菌株Bt T1、Bt T2和Bt T3只产生少量的 2 7kDCyt1Aa蛋白 ,而且部分降解为大约 2 4kD的蛋白。而Bt T4和Bt T5能产生大量的Cyt1Aa蛋白 ,但Bt T4和Bt T5的Cyt1Aa蛋白产量都明显少于Bt WF4 5。电镜观察和生物测定结果表明Bt T4和Bt T5与Bt WF4 5的晶体大小和杀蚊毒力没有显著性差异。研究表明P19和ORF1 ORF2对Cyt1Aa蛋白的合成显示可能有抑制作用。

EFFECTS OF HELPER PROTEINS ENCODED BY p19 AND orf1-orf2 GENES ON Cyt1Aa PROTEIN EXPRESSION IN ACRYSTALLIFEROUSSTRAIN OF BACILLUS THURINGIENSIS

A series of plasmids were constructed to examine the effects of p19 and orf1-orf2 genes from Bacillus thuringiensis on Cyt1Aa synthesis and inclusion formation. The plasmids expressed the cyt1Aa 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 Cyt1Aa protein was found when P19 or Orf1-Orf2 co-expressed with Cyt1Aa. However, when including p20 gene, the constructs with p19 or orf1-orf2 gene produced lower yield of Cyt1Aa proteins than without p19 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 Cyt1Aa protein. It is presumed that P19 and Orf1-Orf2 might have negative effects on Cyt1Aa synthesis in B. thuringiensis.