title: Hsp110 is a nucleotide-activated exchange factor for Hsp70.
abstract: Hsp110 proteins constitute a subfamily of the Hsp70 chaperones and are potent nucleotide exchange factors (NEFs) for canonical Hsp70s of the eukaryotic cytosol. Here, we show that the NEF activity of the yeast Hsp110 homologue Sse1 itself is controlled by nucleotide. Nucleotide binding results in formation of a stabilized conformation of Sse1 that is required for association with the yeast Hsp70 Ssa1. The interaction triggers release of bound ADP from Ssa1, but nucleotide persists bound to Sse1 in the complex. Surprisingly, removal of this nucleotide does not affect the integrity of the complex. Instead, rebinding of ATP to the Hsp70 prompts the dissociation of the complex. Our data demonstrate that in contrast to previously characterized NEFs for Hsp70 chaperones, the NEF activity of Sse1 requires nucleotide binding and let us propose a new model for Hsp110 function.
authors.affiliation: Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZBH Alliance, Heidelberg, Germany.
authors.forename: Claes
authors.initials: C
authors.lastname: Andréasson
authors.forename: Jocelyne
authors.initials: J
authors.lastname: Fiaux
authors.forename: Heike
authors.initials: H
authors.lastname: Rampelt
authors.forename: Matthias P
authors.initials: MP
authors.lastname: Mayer
authors.forename: Bernd
authors.initials: B
authors.lastname: Bukau
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D050957:HSP110 Heat-Shock Proteins / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D008954:Models, Biological; D046912:Multiprotein Complexes / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
chemical_list: D050957:HSP110 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D046912:Multiprotein Complexes; C494656:SSE1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D000244:Adenosine Diphosphate; D000251:Adenosine Triphosphatases; C095973:SSA1 protein, S cerevisiae