Simulation study of the function of domain swapping in the HSP90 chaperone cycle

HSP90 is one of the molecular chaperones, and it is known as an anti-cancer drug target. In the HSP90 chaperone cycle, when the ATP binds to the HSP90NTD, the HSP90 dimer forms a domain swapping in NTD. The stability of the HSP90 dimer is essential to the HSP90 chaperon cycle process. We have performed several molecular dynamics simulations of the HSP90 dimer to investigate how ATP binding and domain swapping have affected the stability. We analysed the fluctuation of critical residues for ATP binding and ATP hydrolysis in the HSP90NTD dimer conformation. As a result, we found that domain swapping is essential to the stability of the HSP90 dimer, while ATP is not so essential for the stability of the dimer conformation.