Construction of high level prokaryotic expression and purification system of PD-L1 extracellular domain by using Escherichia coli host cell machinery

摘要

Programmed cell death 1 ligand 1 (PD-L1) is a trans-membrane protein highly expressed on the membrane of cancer cell, which binds inhibitory receptor of PD-1 on the T cells and attenuates anti-tumor immune response.The strategy of blocking PD1 and PD-L1 interaction has been widely used for anti-cancer drug development. The DNA encoding extracellular domain of PD-L1 was cloned and expressed with the pET30(+) and Escherichia coli BL21(DE3) system. Cloning of PD-L1 extracellular domain was confirmed by PCR and enzymatic digestion. Sequence analysis of cloned targeted genes showed 100% homology of original sequence. The recombinant protein was expressed using 1 mM/mL IPTG and purified by affinity chromatography on a column of Ni-NTA and confirmed by SDS-PAGE and western blot analysis.