title: Determination of the NMR solution structure of the cyclophilin A-cyclosporin A complex.
abstract: The three-dimensional NMR solution structure of the cyclophilin A (Cyp)-cyclosporin A (CsA) complex was determined, and here we provide a detailed description of the analysis of the NMR data and the structure calculation. Using 15N- and 13C-resolved three- and four-dimensional [1H,1H]-nuclear Overhauser enhancement (NOE) spectroscopy with uniformly isotope-labeled Cyp in the complex, a final data set of 1810 intra-Cyp, 107 intra-CsA and 63 intermolecular NOE upper distance constraints was collected as input for the structure calculation with the program DIANA. A group of DIANA conformers, selected by a previously described analysis of the dependence of the maximal root-mean-square deviation (rmsd) among the individual conformers on the residual target function value, was subjected to energy refinement with the program FANTOM. The 22 best energy-refined conformers were then used to represent the solution structure. The average rmsd relative to the mean structure of these 22 conformers is 1.1 A for the backbone atoms of all residues of the complex. The molecular architecture of Cyp in the Cyp-CsA complex includes an eight-stranded antiparallel beta-barrel, which is closed on each side by an amphipathic helix. CsA is bound in a cavity formed by part of the barrel surface and four loops with nonregular secondary structure. Comparison of this structure with structures of Cyp-CsA and other Cyp-peptide complexes determined by different approaches shows extensive similarities.
authors.affiliation: Institut für Molekularbiologie und Biophysik, Eidgenössische Technische Hochschule-Hönggerberg, Zürich, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Spitzfaden
authors.forename: W
authors.initials: W
authors.lastname: Braun
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
mesh_terms: D000591:Amino Acid Isomerases / Q000737:chemistry* / Q000378:metabolism; D000595:Amino Acid Sequence; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism; D016572:Cyclosporine / Q000737:chemistry* / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D019696:Peptidylprolyl Isomerase; D011485:Protein Binding
chemical_list: D002352:Carrier Proteins; D016572:Cyclosporine; D000591:Amino Acid Isomerases; D019696:Peptidylprolyl Isomerase