title: Expression of soluble human Neonatal Fc-receptor (FcRn) in Escherichia coli through modification of growth environment.
abstract: Neonatal Fc-receptor (FcRn) with its affinity to immunoglobulin G (IgG) has been the subject of many pharmacokinetic studies in the past century. This protein is well known for its unique feature in maintaining the circulating IgG from degradation in blood plasma. FcRn is formed by non-covalent association between the α-chain with the β-2-microglobulin (β2m). Many studies have been conducted to produce FcRn in the laboratory, mainly using mammalian tissue culture as host for recombinant protein expression. In this study, we demonstrate a novel strategy to express the α-chain of FcRn using Escherichia coli as the expression host. The expression vector that carries the cDNA of the α-chain was transformed into expression host, Rosetta-gami 2 strain for inducible expression. The bacterial culture was grown in a modified growth medium which constitutes of terrific broth, sodium chloride (NaCl), glucose and betaine. A brief heat shock at 45 °C was carried out after induction, before the temperature for expression was reduced to 22 °C and grown for 16 h. The soluble form of the α-chain of FcRn expressed was tested in the ELISA and dot blot immunoassay to confirm its native functionality. The results implied that the α-chain of FcRn expressed using this method is functional and retains its pH-dependent affinity to IgG. Our study significantly suggests that the activity of human FcRn remain active and functional in the absence of β2m.
authors.affiliation: Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Pulau Pinang, Malaysia.
authors.forename: Woei Kean
authors.initials: WK
authors.lastname: Ng
authors.affiliation: Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Pulau Pinang, Malaysia.
authors.forename: Theam Soon
authors.initials: TS
authors.lastname: Lim
authors.affiliation: Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Pulau Pinang, Malaysia. Electronic address: laingitshin@usm.my.
authors.forename: Ngit Shin
authors.initials: NS
authors.lastname: Lai
mesh_terms: D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development*; D015870:Gene Expression; D015395:Histocompatibility Antigens Class I / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D006801:Humans; D011961:Receptors, Fc / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D012995:Solubility
chemical_list: D015395:Histocompatibility Antigens Class I; D011961:Receptors, Fc; D011994:Recombinant Proteins; C100688:Fc receptor, neonatal
keywords: Betaine; Heat shock; Neonatal Fc-receptor (FcRn); Protein expression; pH dependence; β-2-Microglobulin (β2m)