title: N-terminal domain of human Hsp90 triggers binding to the cochaperone p23.
abstract: The molecular chaperone Hsp90 is a protein folding machine that is conserved from bacteria to man. Human, cytosolic Hsp90 is dedicated to folding of chiefly signal transduction components. The chaperoning mechanism of Hsp90 is controlled by ATP and various cochaperones, but is poorly understood and controversial. Here, we characterized the Apo and ATP states of the 170-kDa human Hsp90 full-length protein by NMR spectroscopy in solution, and we elucidated the mechanism of the inhibition of its ATPase by its cochaperone p23. We assigned isoleucine side chains of Hsp90 via specific isotope labeling of their δ-methyl groups, which allowed the NMR analysis of the full-length protein. We found that ATP caused exclusively local changes in Hsp90's N-terminal nucleotide-binding domain. Native mass spectrometry showed that Hsp90 and p23 form a 22 complex via a positively cooperative mechanism. Despite this stoichiometry, NMR data indicated that the complex was not fully symmetric. The p23-dependent NMR shifts mapped to both the lid and the adenine end of Hsp90's ATP binding pocket, but also to large parts of the middle domain. Shifts distant from the p23 binding site reflect p23-induced conformational changes in Hsp90. Together, we conclude that it is Hsp90's nucleotide-binding domain that triggers the formation of the Hsp90(2)p23(2) complex. We anticipate that our NMR approach has significant impact on future studies of full-length Hsp90 with cofactors and substrates, but also for the development of Hsp90 inhibiting anticancer drugs.
authors.affiliation: Cellular Protein Chemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
authors.forename: G Elif
authors.initials: GE
authors.lastname: Karagöz
authors.forename: Afonso M S
authors.initials: AM
authors.lastname: Duarte
authors.forename: Hans
authors.initials: H
authors.lastname: Ippel
authors.forename: Charlotte
authors.initials: C
authors.lastname: Uetrecht
authors.forename: Tessa
authors.initials: T
authors.lastname: Sinnige
authors.forename: Martijn
authors.initials: M
authors.lastname: van Rosmalen
authors.forename: Jens
authors.initials: J
authors.lastname: Hausmann
authors.forename: Albert J R
authors.initials: AJ
authors.lastname: Heck
authors.forename: Rolf
authors.initials: R
authors.lastname: Boelens
authors.forename: Stefan G D
authors.initials: SG
authors.lastname: Rüdiger
mesh_terms: D000255:Adenosine Triphosphate / Q000737:chemistry; D000495:Allosteric Site; D002138:Calibration; D018841:HSP90 Heat-Shock Proteins / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D019746:Intramolecular Oxidoreductases / Q000737:chemistry*; D007532:Isoleucine / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D000071876:Prostaglandin-E Synthases; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D013053:Spectrophotometry / Q000379:methods
chemical_list: D018841:HSP90 Heat-Shock Proteins; D007532:Isoleucine; D000255:Adenosine Triphosphate; D019746:Intramolecular Oxidoreductases; D000071876:Prostaglandin-E Synthases