CLONING OF PARASPORAL BODY PROTEIN GENE RESEMBLING TO S-LAYER PROTEIN GENES FROM BACILLU THURINGIENSIS CTC STRAIN
类似S-层蛋白的苏云金芽胞杆菌伴胞晶体蛋白基因的克隆

Bacillus CTC strain was identified as Bacillus thuringiensis subsp. finitimus (serotype H2) and Pasteur Institute confirmed this identification. The parasporal body formed by CTC strain is oval shaped, and consists of 100 kD protein. The determination of the N-terminal amino acid sequence showed this protein shares 93% similarity to that of B. anthracis S-layer proteins. The restriction map covering the related protein gene (ctc) was deduced according to southern hybridization. The DNA fragments containing the 5' and 3' end of ctc gene with 0.6 kb overlap were isolated, respectively. Full length ctc gene was then constructed. B. thuringiensis is a species similar to B. cereus and B. anthracis, and only can be distinguished by forming parasporal bodies. The growth of E. coli maintaining ctc gene is similar to that of E. coli expressing S-layer protein gene. The above preliminary results showed that the parasporal body protein in CTC strain is a cell surface-like protein. So identifying CTC strain as a species of B. thuringiensis and the unique criterion for the identification of B. thuringiensis by forming parasporal body should be reconsidered.