title: Fusion of a short peptide that binds immunoglobulin G to a recombinant protein substantially increases its plasma half-life in mice.
abstract: We explore a strategy to substantially increase the half-life of recombinant proteins by genetic fusion to FcIII, a 13-mer IgG-Fc domain binding peptide (IgGBP) originally identified by DeLano and co-workers at Genentech [DeLano WL, et al. (2000) Science 287:1279-1283]. IgGBP fusion increases the in vivo half-life of proteins by enabling the fusion protein to bind serum IgG, a concept originally introduced by DeLano and co-workers in a patent but that to the best of our knowledge has never been pursued in the scientific literature. To further investigate the in vitro and in vivo properties of IgGBP fusion proteins, we fused FcIII to the C-terminus of a model fluorescent protein, monomeric Katushka (mKate). mKate-IgGBP fusions are easily expressed in Escherichia coli and bind specifically to human IgG with an affinity of ∼ 40 nM and ∼ 20 nM at pH 7.4 and pH 6, respectively, but not to mouse or rat IgG isotypes. mKate-IgGBP binds the Fc-domain of hIgG1 at a site overlapping the human neonatal Fc receptor (hFcRn) and as a consequence inhibits the binding of hIgG1 to hFcRn in vitro. High affinity binding to human IgG also endows mKate-IgGBP with a long circulation half-life of ∼ 8 hr in mice, a 75-fold increase compared to unmodified mKate. Thus, IgGBP fusion significantly reduces protein clearance by piggybacking on serum IgG without substantially increasing protein molecular weight due to the small size of the IgGBP. These attractive features could result in protein therapies with reduced dose frequency and improved patient compliance.
authors: Pharmaceutical Sciences and Pharmacogenomics Graduate Program, University of California San Francisco, San Francisco, California, United States of America; Departments of Bioengineering, Therapeutic Sciences and Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, United States of America.
authors: Jonathan T
authors: JT
authors: Sockolosky
authors: Departments of Bioengineering, Therapeutic Sciences and Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, United States of America.
authors: Saul
authors: S
authors: Kivimäe
authors: Pharmaceutical Sciences and Pharmacogenomics Graduate Program, University of California San Francisco, San Francisco, California, United States of America; Departments of Bioengineering, Therapeutic Sciences and Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, United States of America.
authors: Francis C
authors: FC
authors: Szoka
mesh_terms: D000818:Animals; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D004285:Dogs; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005456:Fluorescent Dyes / Q000378:metabolism*; D006207:Half-Life; D015395:Histocompatibility Antigens Class I / Q000235:genetics / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007074:Immunoglobulin G / Q000737:chemistry / Q000378:metabolism*; D061985:Madin Darby Canine Kidney Cells; D051379:Mice; D011485:Protein Binding; D051381:Rats; D011961:Receptors, Fc / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism / Q000493:pharmacokinetics*
chemical_list: D015815:Cell Adhesion Molecules; C106607:FCGBP protein, human; D005456:Fluorescent Dyes; D015395:Histocompatibility Antigens Class I; D007074:Immunoglobulin G; D011961:Receptors, Fc; D011993:Recombinant Fusion Proteins; C100688:Fc receptor, neonatal