Bm-TFF2在毕赤酵母中的表达及鉴定

Bm-TFF2,一种从大蹼铃蟾皮肤分泌物中分离得到的两栖类三叶因子,具有比人三叶因子更强的生物学活性。该研究以Bm-TFF2的cDNA为模板,利用PCR方法扩增Bm-TFF2基因,然后插到含有AOX1启动子和α-因子信号肽序列的表达载体pPIC9K中,采用毕赤酵母表达系统进行分泌表达,并用G418筛选高拷贝整合转化子。SDS-PAGE和Western blotting都检测到Bm-TFF2被分泌性表达于酵母上清。在1%的甲醇诱导表达不同时间后,重组蛋白在72h的表达量最大,可达50mg/L;而不同浓度的饱和硫酸铵沉淀菌液上清时,80%的饱和硫酸铵沉淀量最大。这些结果表明,重组质粒Bm-TFF2-pPIC9K成功构建并在真核细胞中高效表达,这为进一步研究Bm-TFF2的生物学活性及其结构与功能关系奠定了基础。

Expression and identification of Bm-TFF2 in Pichia pastoris

Bm-TFF2, an amphibian trefoil factor, which is isolated from skin secretions of frog Bombina maxima, has much stronger biological activities than human TFFs. In the present study, Bm-TFF2 gene was amplified by polymerase chain reaction (PCR) from its cDNA and cloned into Pichia pastoris expression vector pPIC9K containing AOX1 promoter and alpha -factor leader sequence. Multi-copies insertion transformants were screened on G418 plates. After the induction by 1% methanol for 72 hours, the expression of Bm-TFF2 came up to the best quantity which was about 50 mg in 1L medium, and 80% saturation ammonium sulfate was suitable to collect the Bm-TFF2 protein, as identified by SDS-PAGE and Western blotting assay. The results showed that the plasmid of Bm-TFF2-pPIC9K was constructed successfully and expressed abundantly in eukaryotic expression system, which lies basis for researching further the biological activities and the relationship of structure and functions of Bm-TFF2.