Yu X M, Wang Y, Li Z P
Shanghai Institute of Biochemistry, Academia Sinica, PRC.
Sci China B. 1992 Apr;35(4):455-62.
The N-terminal 54 base pairs (encoding amino acid residues 2-19) within the preS1 region of the human hepatitis B virus surface antigen gene were deleted by site-directed mutagenesis. Unlike the wild type large surface antigen protein, when this mutated gene was expressed in monkey kidney cell line COS-M6, the protein product (S301 protein) could be secreted from the cells. Moreover, the inhibition of the secretion of the major surface antigen protein by this altered large surface antigen protein was greatly reduced, suggesting that the deleted region contained a retention sequence which prevented the secretion of the large surface antigen. However, the coexpression of the major S protein was essential for the secretion of the S301 protein. When coexpressed, the secretion of these two proteins was synchronous. Like the wild type large surface antigen protein, the S301 protein could be translocated into endoplasmic reticulum and glycosylated after its synthesis in COS cells. The S301 protein was thermostable and proteinase-resistant. It also retained the antigenicity of the large S and major S proteins. Given the fact that the S301 protein is readily secretable, stable and identical to the large S protein in terms of their antigenicity, it may be developed into a new generation of recombinant vaccine for the prevention of viral hepatitis.
通过定点诱变删除了乙型肝炎病毒表面抗原基因前S1区的N端54个碱基对（编码氨基酸残基2 - 19）。与野生型大表面抗原蛋白不同，当该突变基因在猴肾细胞系COS - M6中表达时，蛋白质产物（S301蛋白）能够从细胞中分泌出来。此外，这种改变后的大表面抗原蛋白对主要表面抗原蛋白分泌的抑制作用大大降低，这表明缺失区域包含一个阻止大表面抗原分泌的滞留序列。然而，主要S蛋白的共表达对于S301蛋白的分泌至关重要。当共表达时，这两种蛋白的分泌是同步的。与野生型大表面抗原蛋白一样，S301蛋白在COS细胞中合成后能够转运到内质网并进行糖基化。S301蛋白具有热稳定性且抗蛋白酶。它还保留了大S蛋白和主要S蛋白的抗原性。鉴于S301蛋白易于分泌、稳定且在抗原性方面与大S蛋白相同，它可能被开发成为预防病毒性肝炎的新一代重组疫苗。
