title: Importance of cycle timing for the function of the molecular chaperone Hsp90.
abstract: Hsp90 couples ATP hydrolysis to large conformational changes essential for activation of client proteins. The structural transitions involve dimerization of the N-terminal domains and formation of 'closed states' involving the N-terminal and middle domains. Here, we used Hsp90 mutants that modulate ATPase activity and biological function as probes to address the importance of conformational cycling for Hsp90 activity. We found no correlation between the speed of ATP turnover and the in vivo activity of Hsp90: some mutants with almost normal ATPase activity were lethal, and some mutants with lower or undetectable ATPase activity were viable. Our analysis showed that it is crucial for Hsp90 to attain and spend time in certain conformational states: a certain dwell time in open states is required for optimal processing of client proteins, whereas a prolonged population of closed states has negative effects. Thus, the timing of conformational transitions is crucial for Hsp90 function and not cycle speed.
authors.affiliation: Center for Integrated Protein Science Munich, Department of Chemistry, Technische Universität München, Garching, Germany.
authors.forename: Bettina K
authors.initials: BK
authors.lastname: Zierer
authors.affiliation: Center for Integrated Protein Science Munich, Department of Chemistry, Technische Universität München, Garching, Germany.|Institute of Structural Biology, Helmholtz Zentrum München, Neuherberg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Rübbelke
authors.affiliation: Center for Integrated Protein Science Munich, Department of Chemistry, Technische Universität München, Garching, Germany.
authors.forename: Franziska
authors.initials: F
authors.lastname: Tippel
authors.affiliation: Center for Integrated Protein Science Munich, Department of Chemistry, Technische Universität München, Garching, Germany.|Institute of Structural Biology, Helmholtz Zentrum München, Neuherberg, Germany.|Institute of Molecular Biology &Biochemistry, Center of Molecular Medicine, Medical University of Graz, Graz, Austria.
authors.forename: Tobias
authors.initials: T
authors.lastname: Madl
authors.affiliation: Center for Integrated Protein Science Munich, Department of Chemistry, Technische Universität München, Garching, Germany.
authors.forename: Florian H
authors.initials: FH
authors.lastname: Schopf
authors.affiliation: Center for Integrated Protein Science Munich, Department of Chemistry, Technische Universität München, Garching, Germany.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Rutz
authors.affiliation: Center for Integrated Protein Science Munich, Department of Chemistry, Technische Universität München, Garching, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Richter
authors.affiliation: Center for Integrated Protein Science Munich, Department of Chemistry, Technische Universität München, Garching, Germany.|Institute of Structural Biology, Helmholtz Zentrum München, Neuherberg, Germany.
authors.forename: Michael
authors.identifier: http://orcid.org/0000-0002-1594-0527
authors.initials: M
authors.lastname: Sattler
authors.affiliation: Center for Integrated Protein Science Munich, Department of Chemistry, Technische Universität München, Garching, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Buchner
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D018841:HSP90 Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D017354:Point Mutation; D011487:Protein Conformation; D000072417:Protein Domains; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: C074510:HSP82 protein, S cerevisiae; D018841:HSP90 Heat-Shock Proteins; D029701:Saccharomyces cerevisiae Proteins; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases