The influence of the 20kDa protein from Bacillus thuringiensis subsp. israelensis on the cytolytic activity of CytA

In order to understand the influence of the 20kDa protein on the cytolytic activity of CytA protein, a set of PCR primers were designed to amplify 20kDa protein and CytA protein genes. The genes were ligated to E. coli expression vector pUHE24 and transformed into E. coli XL1 and DH5α. The clones, LZ20, LZcytΛ and LZ20A containing 20kDa protein gene, cytA protein gene and 20kDa-cytA genes were obtained respectively. The influence of the clones on the growth of E. coli cells was determined under induction of IPTG. The results showed that the growth of LZ20 cells were not affected, LZcytA cells were killed, and the growth of LZ20A cells were not affected. It was suggested that expression product of 20kDa protein gene protected the host cells from the cytolytic effect of CytA protein. This was supported by using different host strains.