title: Structure of human cyclophilin and its binding site for cyclosporin A determined by X-ray crystallography and NMR spectroscopy.
abstract: The protein cyclophilin is the major intracellular receptor for the immunosuppressive drug cyclosporin A. Cyclosporin A acts as an inhibitor of T-cell activation and can prevent graft rejection in organ and bone marrow transplantation. Cyclophilin may be responsible for mediating this immunosuppressive response. Cyclophilin also catalyses the interconversion of the cis and trans isomers of the peptidyl-prolyl amide bonds of peptide and protein substrates. Here we report the X-ray crystal structure of human recombinant cyclophilin complexed with a tetrapeptide and the identification, by nuclear magnetic resonance spectroscopy, of the specific binding site for cyclosporin A. Cyclophilin has an eight-stranded antiparallel beta-barrel structure. The prolyl isomerase substrate-binding site is coincident with the cyclosporine-binding site. These results may help to provide a structural basis for rationalizing the immunosuppressive function of the cyclosporin-cyclophilin system and will also be important in the design of improved immunosuppressant drugs.
authors.affiliation: Preclinical Research, Sandoz Pharma AG, Basel, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Kallen
authors.forename: C
authors.initials: C
authors.lastname: Spitzfaden
authors.forename: M G
authors.initials: MG
authors.lastname: Zurini
authors.forename: G
authors.initials: G
authors.lastname: Wider
authors.forename: H
authors.initials: H
authors.lastname: Widmer
authors.forename: K
authors.initials: K
authors.lastname: Wüthrich
authors.forename: M D
authors.initials: MD
authors.lastname: Walkinshaw
mesh_terms: D000591:Amino Acid Isomerases / Q000737:chemistry* / Q000378:metabolism; D000595:Amino Acid Sequence; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism; D003524:Cyclosporins / Q000378:metabolism*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019696:Peptidylprolyl Isomerase; D011487:Protein Conformation; D014961:X-Ray Diffraction / Q000379:methods
chemical_list: D002352:Carrier Proteins; D003524:Cyclosporins; D000591:Amino Acid Isomerases; D019696:Peptidylprolyl Isomerase