融合蛋白TAT-RabGEF1原核表达载体的构建及蛋白表达

摘要

[目的]构建PET28a-TAT-RabGEF1重组质粒载体,在E.coli Rosetta(DE3)菌株中高效表达并纯化融合蛋白,研究TAT-RabGEF1融合蛋白对肥大细胞的跨膜转导活性.[方法]以小鼠组织cDNA为模板,设计上游和下游含有限制性酶切位点和TAT序列的引物,PCR扩增目的片段TAT-RabGEF1,并通过双酶切构建PET28a-TAT-Rab-GEF1重组质粒载体,在E.coli Rosetta(DE3)大肠杆菌中诱导表达融合蛋白,产物用亲和层析柱纯化后测量浓度及鉴定.CCK-8检测融合蛋白的细胞毒性,并用荧光显微镜及荧光分光光度计定性定量观察其对小鼠肥大细胞瘤细胞P815的转导活性.[结果]成功构建了PET28a-TAT-RabGEF1重组载体,高效表达了具有较高特异性,相对分子质量约为57 ku的融合蛋白TAT-RabGEF1,0.1、1、10 μmol/L浓度的TAT-RabGEF1蛋白对细胞无明显毒性,荧光显微镜显示1 μmol/L浓度的融合蛋白TAT-RabGEF1具有快速转导进入P815细胞内的能力,且为进入细胞的饱和浓度.[结论]通过TAT-RabGEF1的原核表达和蛋白纯化分析,证实了TAT-PTD的跨膜转导活性,为研究RabGEF1在肥大细胞激活途径中的作用提供了物质基础.%[Objective]To construct recombinant expression vector PET28a-TAT-RabGEF1,express,purify fusion pr-otein effectively in E.coli Rosetta(DE3),and investigate its transmembrane effect in vitro on P815 cells.[Methods]With cDNA in rats′tissues as the template,two primers containing the TAT sequence and two designed enzyme restriction cutting sites were designed. TAT-RabGEF1 fragment was amplified by PCR,and its product was inserted into PET-28a vector to construct recombinant plasmid PET28a-TAT-RabGEF1 prokaryotic expression vector. The recombinant vector was trans-formed into E.coli Rosetta(DE3)and express fusion proteins.The protein products were purified by affinity chromatography. The efficiency of the transduction of fusion protein into P815 cells were detected by immunofluorescence and analyzed by fluo-rescence spectro-photometer,with using methods of CCK-8 to analyze the cells viability after transduction of different con-centrations of fusion protein.[Results]The recombinant vector PET28a-TAT-RabGEF1 was constructed and the fusion pro-tein TAT-RabGEF1 was successfully expressed in E.coli Rosetta(DE3). By western blotting and SDS-PAGE we can see that the protein products′ relative molecular mass was about 57 ku,which was consistent with the target one,TAT-Rab-GEF1.The immunofluorescence results suggested that the fusion protein had the ability to transduct into P815 cells,and sat-uration of fusion proteins to be transducted into cells was 1 μmol/L.[Conclusion]Constructed recombinant vector PET28a-TAT-RabGEF1 and expressed fusion protein,TAT-RabGEF1,which verified the TAT′s ability of transduction. And it would build a solid technical foundation for the following research on the effect of RabGEF1′s on the activation of mast cells.