title: Expression of active murine granulocyte-macrophage colony-stimulating factor in an Escherichia coli cell-free system.
abstract: Granulocyte-macrophage colony-stimulating factor (GM-CSF) is an important cytokine in the mammalian immune system. It has been expressed in Escherichia coli with the same biological activity as the native protein. Here, we report the synthesis of a murine recombinant GM-CSF in an E. coli cell-free protein synthesis system with a high yield. Since there are two disulfide bonds in the native structure of GM-CSF, an oxidizing redox potential of the reaction mixture was required. By pretreating the cell extract with iodoacetamide (IAM), the reducing activity of the cell extract was inactivated, and upon further application of an oxidized glutathione buffer, most of the synthesized GM-CSF was found in its oxidized form. However, the GM-CSF thus formed showed low activity because of poor folding. With the addition of DsbC, the periplasmic disulfide isomerase from E. coli, a high yield of active GM-CSF was produced in the cell-free reaction. Finally, successful folding of the cell-free synthesized GM-CSF-his6 was confirmed by its cell-proliferation activity after purification with a Ni2+ chelating column.
authors.affiliation: Department of Chemical Engineering, Stanford University, Stanford, California 94305, USA.
authors.forename: Junhao
authors.initials: J
authors.lastname: Yang
authors.forename: Gregory
authors.initials: G
authors.lastname: Kanter
authors.forename: Alexei
authors.initials: A
authors.lastname: Voloshin
authors.forename: Ronald
authors.initials: R
authors.lastname: Levy
authors.forename: James R
authors.initials: JR
authors.lastname: Swartz
mesh_terms: D000818:Animals; D002474:Cell-Free System; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D024861:Genetic Enhancement / Q000379:methods; D016179:Granulocyte Colony-Stimulating Factor / Q000096:biosynthesis* / Q000737:chemistry*; D051379:Mice; D015202:Protein Engineering / Q000379:methods*; D011994:Recombinant Proteins
chemical_list: D011994:Recombinant Proteins; D016179:Granulocyte Colony-Stimulating Factor