Computational investigation of interactions between Cdc37 and celastrol

Celastrol is a novel inhibitor of the human protein complex Hsp90–Cdc37. It was found that the N-terminal domain of Cdc37 (Cdc37_N) was the molecular target for celastrol binding through covalent bonding. To get insight into the binding mode of celastrol in the active site of Cdc37, herein, the homology models of Cdc37_N and N-terminal/middle domain of Cdc37 (Cdc37_NM) were built. Moreover, a model of Cdc37 complexed with celastrol was obtained using docking and molecular dynamics (MD) approaches. Molecular modelling studies indicated that the middle domain of Cdc37 (Cdc37_M) might be an obbligato part of the binding pocket, which could make the pocket stable for celastrol docking. We also found that the S atom of Cys57 was closest to C6 atom of celastrol among all three cysteine residues (Cys54, Cys57 and Cys64) in the pocket, which implied that celastrol and Cys57 did have a good chance to form covalent bond. The covalent interaction between C6 atom of celastrol and Cys57 of Cdc37 could also explain the...