Expression and purification of soluble human APRIL in Escherichia coli using ELP-SUMO tag.

APRIL is a member of the tumor necrosis factor (TNF) family of ligands that mediate tumor cells proliferation as well as survival, depending on the cellular context. In this report, we present a novel method to obtain soluble human APRIL in Escherichia coli using the elastin-like polypeptide and SUMO (ELP-SUMO) tags. The fusion protein with ELP-SUMO tag was expressed in a soluble form at 15°C. After purification based on inverse transition cycling (ITC) method, the purified ELP-SUMO-hAPRIL fusion protein was subsequently cleaved by SUMO protease to release mature hAPRIL. Following affinity chromatography, the target protein was re-purified with high purity. Finally, about 4.8mg recombinant hAPRIL was obtained from 1l bacterial culture with no less than 85% purity. The molecular mass (Mr) of the recombinant hAPRIL was confirmed by MALDI-TOF MS as Mr 16,314. The purified hAPRIL exhibits biological activity on Jurkat cells. It is the first report on soluble production of hAPRIL in E. coli using ELP-SUMO tag.