生长抑素(SS)基因在大肠杆菌pT7ZZ表达系统中的克隆与表达

目的 构建和筛选既能稳定、高效表达SS融合蛋白，又能使这种融合蛋白保持良好的SS抗原性和高水溶性等特点的重组质粒。方法 用 BamH I/Xho I (B/X）和 BamH I/EcoR I（B/E）双酶切，将含有SS基因的片段由pThioHis A中切出，然后分别克隆到 pT7ZZa中的相应酶切位点，得到pSSB/X（短尾）和pSS-B/E(长尾)两个重组质粒，用常规表达技术在大肠杆菌中对其进行表达。结果 pSS-B/X和pSS-B/E两个重组质粒在宿主菌BL21（DE3）中均获得表达，pSS-B/X获得高效表达后融合蛋白占菌体总蛋白的30．6％。两个表达菌经超声裂解后电泳发现，SS－B/X－ZZ和SS－B/E－ZZ这两种融合蛋白基本为可溶性蛋白，沉淀中含量极低。二者均具有良好的抗原性，结论pSS-B/X重组质粒很有希望成为SS基因疫苗的候选质粒。

Cloning and Expression of Somatostatin (SS) Gene in E.coli pT7ZZ System

Abstract: Objective To construct and screen a recombinant plasmid for stable and high expression of SS fusion protein with antigenicity and high water solubility . Methods Recombinant plasmids pSS - B/X (short tail)and pSS - B/E(long tail) were construced by cutting out 2 SS gene fragments from plasmid pThio-His A by BamH I/Xho I (B/X) and BamH I/EcoR I(B/E) and cloning them into the corresponding sites of plasmid pT7ZZa respectively, then expressed in E. coli by conventional technology. Results Both pSS - B/E and pSS - B/X were expressed in BL21(DE3) .The expressed product of pSS - B/X contained 30.6% of the total somatic protein.The electrophoretic analysis after ultrasonication showed that almost all the fusion proteins SS - B/X - ZZ and SS - B/E - ZZ were soluble, and both of them showed good antigenicity. Conclusion pSS - B/X might be a candidate plasmid for developing recombinant SS vaccine.