苏云金芽胞杆菌CTC菌株的S-层蛋白可以形成伴胞晶体

苏云金芽胞杆菌(Bacillus thuringiensis)CTC菌株产生卵圆形伴胞晶体，晶体蛋白分子量为100kD；透射电子显微镜观察结果表明该菌株有S—层结构，而且在母细胞内可以形成伴胞晶体和S—层的初体结构；其蛋白基因导入苏云金芽胞杆菌无晶体突变株BMB171后，扫描电子显微镜观察结果表明转化子能形成晶体，而其形状与CTC菌株的相同；转化子晶体蛋白的分子量大小也与CTC菌株的相同，为100kD。以上实验结果结合以前晶体蛋白N—末端测序和基因核苦酸序列，表明苏云金芽胞杆菌CTC菌株的S—层蛋白可以形成伴胞晶体。

The S-Layer Protein of Bacillus thuringiensis CTC Strain Forms Parasporal Crystals

Bacillus thuringiensis strain CTC forms ellipsoid crystals. Transmission electron microscope observation showed that CTC cells had a clear S-layer. It was found that CTC strain formed parasporal crystals during sporulation and preliminary structure of S-layer inside the cells. After the crystal protein encoding gene ctc was transformed into the crystal negative Bacillus thuringiensis strain BMB171, the transformats could also form crystals similar to those of strain CTC as observed under scanning electron microscope. SDS-PAGE showed that the molecular weight of crystal protein product in recombinant strain BMB171 was identical to that of strain CTC. It was concluded that the S-layer proteins of CTC strain can form parasporal crystals, along with previous results that both the N-terminal aminto acid sequence of crystal protein and the DNA sequence of the encoding gene ctc showed high homologous with those of S-layer proteins.