title: Crystallization and preliminary X-ray analysis of a 1:1 complex between a designed monomeric interferon-gamma and its soluble receptor.
abstract: A variant of human interferon-gamma (IFN-gamma) has been created in which the two chains of the homodimeric cytokine were linked N- to C-terminus by an eight residue polypeptide linker. The sequence of this linker was derived from a loop in bira bifunctional protein, and was determined from a structural database search. This "single-chain" variant was used to create an IFN-gamma molecule that binds only a single copy of the alpha-chain receptor, rather than the 2 alpha-chain receptor: 1 IFN-gamma binding stoichiometry observed for the native hormone. Crystals have been grown of a 1:1 complex between this single-chain molecule and the extracellular domain of its alpha-chain receptor. These crystals diffract beyond 2.0 A, significantly better than the 2.9 A observed for the native 2:1 complex. Density calculations suggest these crystals contain two complexes in the asymmetric unit; a self-rotation function confirms this conclusion.
authors.affiliation: Graduate Group in Biophysics, University of California, San Francisco 94000, USA.
authors.forename: M
authors.initials: M
authors.lastname: Randal
authors.forename: A A
authors.initials: AA
authors.lastname: Kossiakoff
mesh_terms: D000818:Animals; D002417:Cattle; D003460:Crystallization; D018360:Crystallography, X-Ray; D019281:Dimerization; D004926:Escherichia coli / Q000235:genetics; D006801:Humans; D007371:Interferon-gamma / Q000737:chemistry*; D008958:Models, Molecular; D008970:Molecular Weight; D016296:Mutagenesis / Q000235:genetics; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017471:Receptors, Interferon / Q000737:chemistry*; D011994:Recombinant Proteins / Q000737:chemistry
chemical_list: D017471:Receptors, Interferon; D011994:Recombinant Proteins; D007371:Interferon-gamma