title: Binding of a small molecule at a protein-protein interface regulates the chaperone activity of hsp70-hsp40.
abstract: Heat shock protein 70 (Hsp70) is a highly conserved molecular chaperone that plays multiple roles in protein homeostasis. In these various tasks, the activity of Hsp70 is shaped by interactions with co-chaperones, such as Hsp40. The Hsp40 family of co-chaperones binds to Hsp70 through a conserved J-domain, and these factors stimulate ATPase and protein-folding activity. Using chemical screens, we identified a compound, 115-7c, which acts as an artificial co-chaperone for Hsp70. Specifically, the activities of 115-7c mirrored those of a Hsp40; the compound stimulated the ATPase and protein-folding activities of a prokaryotic Hsp70 (DnaK) and partially compensated for a Hsp40 loss-of-function mutation in yeast. Consistent with these observations, NMR and mutagenesis studies indicate that the binding site for 115-7c is adjacent to a region on DnaK that is required for J-domain-mediated stimulation. Interestingly, we found that 115-7c and the Hsp40 do not compete for binding but act in concert. Using this information, we introduced additional steric bulk to 115-7c and converted it into an inhibitor. Thus, these chemical probes either promote or inhibit chaperone functions by regulating Hsp70-Hsp40 complex assembly at a native protein-protein interface. This unexpected mechanism may provide new avenues for exploring how chaperones and co-chaperones cooperate to shape protein homeostasis.
authors.affiliation: Department of Pathology and the Life Sciences Institute, University of Michigan, Ann Arbor, USA.
authors.forename: Susanne
authors.initials: S
authors.lastname: Wisén
authors.forename: Eric B
authors.initials: EB
authors.lastname: Bertelsen
authors.forename: Andrea D
authors.initials: AD
authors.lastname: Thompson
authors.forename: Srikanth
authors.initials: S
authors.lastname: Patury
authors.forename: Peter
authors.initials: P
authors.lastname: Ung
authors.forename: Lyra
authors.initials: L
authors.lastname: Chang
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Evans
authors.forename: Gladis M
authors.initials: GM
authors.lastname: Walter
authors.forename: Peter
authors.initials: P
authors.lastname: Wipf
authors.forename: Heather A
authors.initials: HA
authors.lastname: Carlson
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Brodsky
authors.forename: Erik R P
authors.initials: ER
authors.lastname: Zuiderweg
authors.forename: Jason E
authors.initials: JE
authors.lastname: Gestwicki
mesh_terms: D004926:Escherichia coli / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D050956:HSP40 Heat-Shock Proteins / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D054852:Small Molecule Libraries / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D029968:Escherichia coli Proteins; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D029701:Saccharomyces cerevisiae Proteins; D054852:Small Molecule Libraries; C063842:dnaK protein, E coli