title: The fibronectin type III domain as a scaffold for novel binding proteins.
abstract: The fibronectin type III domain (FN3) is a small autonomous folding unit which occurs in many animal proteins involving in ligand binding. The beta-sandwich structure of FN3 closely resembles that of immunoglobulin domains. We have prepared a phage display library of FN3 in which residues in two surface loops were randomized. We have selected mutant FN3s which bind to a test ligand, ubiquitin, with significant affinities, while the wild-type FN3 shows no measurable affinity. A dominant clone was expressed as a soluble protein and its properties were investigated in detail. Heteronuclear NMR characterization revealed that the selected mutant protein retains the global fold of FN3. It also has a modest conformational stability despite mutations at 12 out of 94 residues. These results clearly show the potential of FN3 as a scaffold for engineering novel binding proteins.
authors.affiliation: Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, NY, 14642, USA.
authors.forename: A
authors.initials: A
authors.lastname: Koide
authors.forename: C W
authors.initials: CW
authors.lastname: Bailey
authors.forename: X
authors.initials: X
authors.lastname: Huang
authors.forename: S
authors.initials: S
authors.lastname: Koide
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017104:Bacteriophage M13 / Q000235:genetics; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004274:DNA, Recombinant / Q000235:genetics; D005353:Fibronectins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis; D011487:Protein Conformation; D015202:Protein Engineering; D017510:Protein Folding; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D004274:DNA, Recombinant; D005353:Fibronectins; D011994:Recombinant Proteins