Construction of Prokaryotic Expression Plasmid of the Human Tumor Suppressor Gene PTEN and Its Expression in E.coli

To study the function of PTEN protein,the recombinant pET-Nus-PTEN was constructed and expressed in BL21(DE3) E.coli.Positive pMD-PTEN plasmid was digested with EcoR I and Sal I and the PTEN cDNA fragment was ligated to prokaryotic expression vector pET-44a which also been digested with EcoR I and Sal I.Sequence analysis proved that the prokaryotic expression plasmid of PTEN have been constructed successfully.The recombinant plasmid was transformed into BL21(DE3) E.coli.The expression of Nus-PTEN was induced with IPTG,and the expressed product was detected by 12% SDS-PAGE.The target protein was about 118kD and the expression level accounted for 17% of the total cellular protein.The results showed that PTEN protein was expressed fusing with Nus Tag in soluble form.This research has laid foundation for investigating the tumor suppression mechanism of PTEN protein and the probability of genetically engineered medicine of PTEN.This is the first report of PTEN expression in prokaryotic cells in China.