title: Biological and structural basis for Aha1 regulation of Hsp90 ATPase activity in maintaining proteostasis in the human disease cystic fibrosis.
abstract: The activator of Hsp90 ATPase 1, Aha1, has been shown to participate in the Hsp90 chaperone cycle by stimulating the low intrinsic ATPase activity of Hsp90. To elucidate the structural basis for ATPase stimulation of human Hsp90 by human Aha1, we have developed novel mass spectrometry approaches that demonstrate that the N- and C-terminal domains of Aha1 cooperatively bind across the dimer interface of Hsp90 to modulate the ATP hydrolysis cycle and client activity in vivo. Mutations in both the N- and C-terminal domains of Aha1 impair its ability to bind Hsp90 and stimulate its ATPase activity in vitro and impair in vivo the ability of the Hsp90 system to modulate the folding and trafficking of wild-type and variant (DeltaF508) cystic fibrosis transmembrane conductance regulator (CFTR) responsible for the inherited disease cystic fibrosis (CF). We now propose a general model for the role of Aha1 in the Hsp90 ATPase cycle in proteostasis whereby Aha1 regulates the dwell time of Hsp90 with client. We suggest that Aha1 activity integrates chaperone function with client folding energetics by modulating ATPase sensitive N-terminal dimer structural transitions, thereby protecting transient folding intermediates in vivo that could contribute to protein misfolding systems disorders such as CF when destabilized.
authors.affiliation: Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
authors.forename: Atanas V
authors.initials: AV
authors.lastname: Koulov
authors.forename: Paul
authors.initials: P
authors.lastname: LaPointe
authors.forename: Bingwen
authors.initials: B
authors.lastname: Lu
authors.forename: Abbas
authors.initials: A
authors.lastname: Razvi
authors.forename: Judith
authors.initials: J
authors.lastname: Coppinger
authors.forename: Meng-Qiu
authors.initials: MQ
authors.lastname: Dong
authors.forename: Jeanne
authors.initials: J
authors.lastname: Matteson
authors.forename: Rob
authors.initials: R
authors.lastname: Laister
authors.forename: Cheryl
authors.initials: C
authors.lastname: Arrowsmith
authors.forename: John R
authors.initials: JR
authors.lastname: Yates
authors.forename: William E
authors.initials: WE
authors.lastname: Balch
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D003550:Cystic Fibrosis / Q000201:enzymology* / Q000235:genetics; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018841:HSP90 Heat-Shock Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods*; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D011487:Protein Conformation; D017510:Protein Folding; D055503:Protein Multimerization; D016415:Sequence Alignment
chemical_list: C515652:AHSA1 protein, human; D018841:HSP90 Heat-Shock Proteins; D018832:Molecular Chaperones; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D000255:Adenosine Triphosphate