NMR studies of (U- sup 13 C)cyclosporin A bound to cyclophilin: Bound conformation and protions of cyclosporin involved in binding

• Published in: Biochemistry (Easton) 1991-07, Vol.30:26
• Main Authors: Fesik, S.W., Gampe, R.T. Jr, Eaton, H.L., Gemmecker, G., Olejniczak, E.T., Neri, P., Holzman, T.F., Egan, D.A., Edalji, R., Simmer, R., Helfrich, R., Hochlowski, J., Jackson, M.
• Format: Article
• Language: English
• Subjects: 550201 - Biochemistry- Tracer Techniques; BASIC BIOLOGICAL SCIENCES; CARBON 13; CARBON ISOTOPES; CHEMICAL SHIFT; DRUGS; EVEN-ODD NUCLEI; GEOMETRY; IMMUNOSUPPRESSION; IMMUNOSUPPRESSIVE DRUGS; ISOTOPES; LIGHT NUCLEI; MAGNETIC RESONANCE; MATHEMATICS; NUCLEAR MAGNETIC RESONANCE; NUCLEI; ORGANIC COMPOUNDS; OVERHAUSER EFFECT; PROTEINS; RESONANCE; STABLE ISOTOPES; STEREOCHEMISTRY; STRUCTURE-ACTIVITY RELATIONSHIPS
• ISSN: 0006-2960; 1520-4995
• DOI: 10.1021/bi00240a030

Cyclosporin A (CsA), a potent immunosuppressant, is known to bind with high specificity to cyclophilin (CyP), a 17.7 kDa protein with peptidyl-prolyl isomerase activity. In order to investigate the three-dimensional structure of the CsA/CyP complex, the authors have applied a variety of multidimensional NMR methods in the study of uniformly {sup 13}C-labeled CsA bound to cyclophilin. The {sup 1}H and {sup 13}C NMR signals of cyclosporin A in the bound state have been assigned, and, from a quantitative interpretation of the 3D NOE data, the bound conformation of CsA has been determined. Three-dimensional structures of CsA calculated from the NOE data by using a distance geometry/simulated annealing protocol were found to be very different form previously determined crystalline and solution conformations of uncomplexed CsA. In addition, from CsA/CyP NOEs, the portions of CsA that interact with cyclophilin were identified. For the most part, those CsA residues with NOEs to cyclophilin were the same residues important for cyclophilin binding and immunosuppressive activity as determined from sturcture/activity relationships. The structural information derived in this study together with the known structure/activity relationships for CsA analogues may prove useful in the design of improved immunosuppressants. Moreover, the approach that is described for obtaining the structural information is widely applicable to the study of small molecule/large molecule interactions.