Modeling of the Full-Size 3D Structure of Human Chaperone Hsp70 and Study of Its Interdomain Interactions.

Hsp70 is a chaperone protein that participates in the folding of de novo synthesized proteins, protection of the hydrophobic regions of denaturated proteins, the regulation of apoptosis, the immune response, and several other cellular processes. Despite the large number of publications devoted to the functioning and structure of Hsp70, a reliable full-size 3D structure of this protein remains currently unavailable. Several probable full-size models of human Hsp70 have been constructed based on the structures of individual domains and their components from different organisms and using molecular modeling methodology. The stability of the obtained structures was studied using molecular dynamics. As a result of such an analysis, the most adequate model was selected. The model was built on the basis of Hsp70 elements fromBos TaurusandCaenorhabditis elegans. Using the method of steered molecular dynamics, the key salt bridges responsible for the interdomain interactions were identified: Arg171: Glu516 and Arg416: Glu218. Based on the performed molecular modeling, the scheme of the mechanism triggering ATP hydrolysis and leading to the separation of ATPase and the substrate-binding domains was proposed.