title: Species-dependent ensembles of conserved conformational states define the Hsp90 chaperone ATPase cycle.
abstract: The molecular chaperone heat shock protein 90 (Hsp90) is required for the folding and activation of numerous essential signaling proteins. Hsp90 is generally thought to transition between an open (apo) and a closed (ATP) conformation in response to nucleotide. Here, 3D single-particle reconstructions of Escherichia coli and yeast Hsp90 homologs establish the existence of two distinct nucleotide-stabilized conformations (ATP, ADP) in addition to an apo extended state, supporting previous structural work. However, single-particle matching methods reveal that, rather than being irreversibly determined by nucleotide, a species-dependent dynamic conformational equilibrium exists between states. Using crosslinking methods, we trap transient nucleotide-specific states of yeast and human Hsp90 and establish that the apo, ATP, and ADP states are universal. These data support a conserved three-state chaperone cycle where the conformational equilibrium varies between species, implicating evolutionary tuning to meet the particular client protein and metabolic environment of an organism.
authors.affiliation: Howard Hughes Medical Institute and Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Southworth
authors.forename: David A
authors.initials: DA
authors.lastname: Agard
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000266:Adenylyl Imidodiphosphate / Q000378:metabolism; D003432:Cross-Linking Reagents / Q000494:pharmacology; D019281:Dimerization; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000648:ultrastructure; D018841:HSP90 Heat-Shock Proteins / Q000737:chemistry* / Q000648:ultrastructure; D006801:Humans; D008854:Microscopy, Electron; D008958:Models, Molecular; D055550:Protein Stability / Q000187:drug effects; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000648:ultrastructure; D013045:Species Specificity
chemical_list: D003432:Cross-Linking Reagents; D029968:Escherichia coli Proteins; D018841:HSP90 Heat-Shock Proteins; C489352:HtpG protein, E coli; D029701:Saccharomyces cerevisiae Proteins; D000266:Adenylyl Imidodiphosphate; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases