The force-dependent mechanism of DnaK-mediated mechanical folding

TitleThe force-dependent mechanism of DnaK-mediated mechanical folding
Publication TypeJournal Article
Year of Publication2018
AuthorsPerales-Calvo J, Giganti D, Stirnemann G, Garcia-Manyes S
JournalSci Adv
Volume4
Paginationeaaq0243
Date PublishedFeb
Abstract

It is well established that chaperones modulate the protein folding free-energy landscape. However, the molecular determinants underlying chaperone-mediated mechanical folding remain largely elusive, primarily because the force-extended unfolded conformation fundamentally differs from that characterized in biochemistry experiments. We use single-molecule force-clamp spectroscopy, combined with molecular dynamics simulations, to study the effect that the Hsp70 system has on the mechanical folding of three mechanically stiff model proteins. Our results demonstrate that, when working independently, DnaJ (Hsp40) and DnaK (Hsp70) work as holdases, blocking refolding by binding to distinct substrate conformations. Whereas DnaK binds to molten globule-like forms, DnaJ recognizes a cryptic sequence in the extended state in an unanticipated force-dependent manner. By contrast, the synergetic coupling of the Hsp70 system exhibits a marked foldase behavior. Our results offer unprecedented molecular and kinetic insights into the mechanisms by which mechanical force finely regulates chaperone binding, directly affecting protein elasticity.

DOI10.1126/sciadv.aaq0243
Citation Key2018|2132
PubMed ID29487911