title: Hsp70 targets Hsp100 chaperones to substrates for protein disaggregation and prion fragmentation.
abstract: Hsp100 and Hsp70 chaperones in bacteria, yeast, and plants cooperate to reactivate aggregated proteins. Disaggregation relies on Hsp70 function and on ATP-dependent threading of aggregated polypeptides through the pore of the Hsp100 AAA(+) hexamer. In yeast, both chaperones also promote propagation of prions by fibril fragmentation, but their functional interplay is controversial. Here, we demonstrate that Hsp70 chaperones were essential for species-specific targeting of their Hsp100 partner chaperones ClpB and Hsp104, respectively, to heat-induced protein aggregates in vivo. Hsp70 inactivation in yeast also abrogated Hsp104 targeting to almost all prions tested and reduced fibril mobility, which indicates that fibril fragmentation by Hsp104 requires Hsp70. The Sup35 prion was unique in allowing Hsp70-independent association of Hsp104 via its N-terminal domain, which, however, was nonproductive. Hsp104 overproduction even outcompeted Hsp70 for Sup35 prion binding, which explains why this condition prevented Sup35 fragmentation and caused prion curing. Our findings indicate a conserved mechanism of Hsp70-Hsp100 cooperation at the surface of protein aggregates and prion fibrils.
authors.affiliation: Center for Molecular Biology of the University of Heidelberg and German Cancer Research Center, DKFZ-ZMBH Alliance, Universität Heidelberg, Heidelberg D-69120, Germany.
authors.forename: Juliane
authors.initials: J
authors.lastname: Winkler
authors.forename: Jens
authors.initials: J
authors.lastname: Tyedmers
authors.forename: Bernd
authors.initials: B
authors.lastname: Bukau
authors.forename: Axel
authors.initials: A
authors.lastname: Mogk
mesh_terms: D049071:Endopeptidase Clp; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000378:metabolism; D005456:Fluorescent Dyes / Q000494:pharmacology; D049452:Green Fluorescent Proteins / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000378:metabolism*; D008856:Microscopy, Fluorescence / Q000379:methods; D018832:Molecular Chaperones / Q000378:metabolism; D010454:Peptide Termination Factors / Q000737:chemistry; D010455:Peptides / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D011328:Prions / Q000737:chemistry* / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry; D013997:Time Factors
chemical_list: D029968:Escherichia coli Proteins; D005456:Fluorescent Dyes; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D010454:Peptide Termination Factors; D010455:Peptides; D011328:Prions; D011506:Proteins; C068068:SUP35 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C070972:HsP104 protein, S cerevisiae; D049452:Green Fluorescent Proteins; D049071:Endopeptidase Clp; C069775:ClpB protein, E coli