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Crystallization and preliminary X‐ray analysis of a 1:1 complex between a designed monomeric interferon‐gamma and its soluble receptor
Author(s) -
Randal M.,
Kossiakoff A. A.
Publication year - 1998
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.5560070424
Subject(s) - linker , crystallography , monomer , crystallization , molecule , chemistry , stoichiometry , residue (chemistry) , receptor , polypeptide chain , macromolecule , stereochemistry , biochemistry , amino acid , organic chemistry , computer science , operating system , polymer
A variant of human interferon‐gamma (IFN‐γ) 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‐γ molecule that binds only a single copy of the α‐chain receptor, rather than the 2 α‐chain receptor: 1 IFN‐γ 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 α‐chain receptor. These crystals diffract beyond 2.0 Å, significantly better than the 2.9 Å 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.