Maltose binding protein facilitates functional production of engineered human chemokine receptor 3 in Escherichia coli

Abstract

Human C-C chemokine receptor 3 (CCR3), belonging to the G protein-coupled receptor (GPCR) family, plays a central role in various allergic diseases. Although good understanding on this protein is of critical importance to drug design, studies on the structure and functions of CCR3 are still limited, mainly due to the difficulties to obtain a large quantity of pure and functional protein. Here we report high-level production of human CCR3 fused to maltose binding protein (MBP) in Escherichia coli. Over-expression of MBP-CCR3 was achieved by systematically optimizing expression conditions, and Fos choline-14 was found to be an optimum surfactant for solubilization and stabilization of MBP-CCR3 in purification. After the two-step chromatography purification, the yield of MBP-CCR3 was 2–4mg/l culture. The binding activity of purified MBP-CCR3 was verified by binding with its endogenous ligands CCL11 and CCL24, with KD of 2.90×10−6 and 1.81×10−6M, respectively. This is the first report for that MBP fused recombinant CCR3 (MBP-CCR3) produced in E. coli still maintains its binding activity with its endogenous ligands, which provides an efficient way to produce functional GPCR proteins at large scale for further structural and functional studies.