title: Soluble prokaryotic overexpression and purification of bioactive human granulocyte colony-stimulating factor by maltose binding protein and protein disulfide isomerase.
abstract: Human granulocyte colony-stimulating factor (hGCSF), a neutrophil-promoting cytokine, is an effective therapeutic agent for neutropenia patients who have undergone several cancer treatments. Efficient production of hGCSF using E. coli is challenging because the hormone tends to aggregate and forms inclusion bodies. This study examined the ability of seven different N-terminal fusion tags to increase expression of soluble hGCSF in E. coli. Four tag proteins, namely maltose-binding protein (MBP), N-utilization substance protein A, protein disulfide isomerase (PDI), and the b'a' domain of PDI (PDIb'a'), increased the solubility of hGCSF under normal conditions. Lowering the expression temperature from 30°C to 18°C also increased the solubility of thioredoxin-tagged and glutathione S-transferase-tagged hGCSF. By contrast, hexahistidine-tagged hGCSF was insoluble at both temperatures. Simple conventional chromatographic methods were used to purify hGCSF from the overexpressed PDIb'a'-hGCSF and MBP-hGCSF proteins. In total, 11.3 mg or 10.2 mg of pure hGCSF were obtained from 500 mL cultures of E. coli expressing PDIb'a'-hGCSF or MBP-hGCSF, respectively. SDS-PAGE analysis and silver staining confirmed high purity of the isolated hGCSF proteins, and the endotoxin levels were less than 0.05 EU/µg of protein. Subsequently, the bioactivity of the purified hGCSF proteins similar to that of the commercially available hGCSF was confirmed using the mouse M-NFS-60 myelogenous leukemia cell line. The EC50s of the cell proliferation dose-response curves for hGCSF proteins purified from MBP-hGCSF and PDIb'a'-hGCSF were 2.83±0.31 pM, and 3.38±0.41 pM, respectively. In summary, this study describes an efficient method for the soluble overexpression and purification of bioactive hGCSF in E. coli.
authors.affiliation: Department of Physiology and Biomedical Institute of Technology, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Bich Hang
authors.initials: BH
authors.lastname: Do
authors.affiliation: Department of Physiology and Biomedical Institute of Technology, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Han-Bong
authors.initials: HB
authors.lastname: Ryu
authors.affiliation: Department of Physiology and Biomedical Institute of Technology, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Phuong
authors.initials: P
authors.lastname: Hoang
authors.affiliation: Department of Physiology and Biomedical Institute of Technology, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Bon-Kyung
authors.initials: BK
authors.lastname: Koo
authors.affiliation: Department of Physiology and Biomedical Institute of Technology, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Han
authors.initials: H
authors.lastname: Choe
mesh_terms: D049109:Cell Proliferation; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics; D016179:Granulocyte Colony-Stimulating Factor / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D058619:Maltose-Binding Proteins / Q000378:metabolism*; D019704:Protein Disulfide-Isomerases / Q000378:metabolism*
chemical_list: D058619:Maltose-Binding Proteins; D016179:Granulocyte Colony-Stimulating Factor; D019704:Protein Disulfide-Isomerases