Characterization of Folding Cores in the Cyclophilin A-Cyclosporin A Complex

Jack W. Heal, Stephen A. Wells, Claudia A. Blindauer, Robert B. Freedman, Rudolf A. Roemer

OAI: oai:purehost.bath.ac.uk:publications/d379f7bb-0dc3-46cf-8e92-0142a304b837 • DOI: https://doi.org/10.1016/j.bpj.2015.02.017

Determining the folding core of a protein yields information about its folding process and dynamics. The experimental procedures for identifying the amino acids that make up the folding core include hydrogen-deuterium exchange and F-value analysis and can be expensive and time consuming. Because of this, there is a desire to improve upon existing methods for determining protein folding cores theoretically. We have obtained HDX data for the complex of cyclophilin A with the immunosuppressant cyclosporin A. We compare these data, as well as literature values for uncomplexed cyclophilin A, to theoretical predictions using a combination of rigidity analysis and coarse-grained simulations of protein motion. We find that in this case, the most specific prediction of folding cores comes from a combined approach that models the rigidity of the protein using the First software suite and the dynamics of the protein using the FRODA tool.