The Optimization of Soluble PTEN Expression in Escherichia coli

摘要

As a vital tumor suppressor, PTEN (Phosphatase and tension homolog deleted on chromosome 10) is involvedin inherited syndromes, and is among the most frequently inactivated tumor suppressor gene in sporadic cancers. PTENloss-of-function widely occurs in human cancers via a variety of mechanisms, including genetic alterations and posttranslationalmodification. These suggest PTEN has a role of functional importance in a variety of cancers. In the presentstudy, we constructed a prokaryotic expression vector that efficiently expresses GST-PTEN (the target protein in whichPTEN is fused with glutathione S-transferase tag) in E. coli. We found that the target protein was partially soluble althoughmajor portions of the protein remained in the inclusion bodies. Furthermore, we explored the optimal inductiontemperature, isopropyl β-D-1-thiogalactopyranoside (IPTG) concentration and induction time in a series of experiments.Expression level analysis indicated that PTEN reached its peak level at 36○C for 8 h with 1.5625mM IPTG, while solubilityanalysis revealed the optimal induction temperature was at 20○C, the optimal IPTG concentration was 0.1μM and theoptimal induction time was up to 8 h. Taken together, we provide an optimal induction condition for expressing solublefusion protein of PTEN in E. coli, facilitating further analysis of PTEN’s biological function in vitro.