title: Structural and functional basis of protein phosphatase 5 substrate specificity.
abstract: The serine/threonine phosphatase protein phosphatase 5 (PP5) regulates hormone- and stress-induced cellular signaling by association with the molecular chaperone heat shock protein 90 (Hsp90). PP5-mediated dephosphorylation of the cochaperone Cdc37 is essential for activation of Hsp90-dependent kinases. However, the details of this mechanism remain unknown. We determined the crystal structure of a Cdc37 phosphomimetic peptide bound to the catalytic domain of PP5. The structure reveals PP5 utilization of conserved elements of phosphoprotein phosphatase (PPP) structure to bind substrate and provides a template for many PPP-substrate interactions. Our data show that, despite a highly conserved structure, elements of substrate specificity are determined within the phosphatase catalytic domain itself. Structure-based mutations in vivo reveal that PP5-mediated dephosphorylation is required for kinase and steroid hormone receptor release from the chaperone complex. Finally, our data show that hyper- or hypoactivity of PP5 mutants increases Hsp90 binding to its inhibitor, suggesting a mechanism to enhance the efficacy of Hsp90 inhibitors by regulation of PP5 activity in tumors.
authors.affiliation: Institute of Structural and Molecular Biology, Biological Sciences, University College London and Birkbeck College, London WC1E 7HX, United Kingdom;
authors.forename: Jasmeen
authors.initials: J
authors.lastname: Oberoi
authors.affiliation: Department of Urology, State University of New York Upstate Medical University, Syracuse, NY 13210; Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, NY 13210; Cancer Research Institute, State University of New York Upstate Medical University, Syracuse, NY 13210.
authors.forename: Diana M
authors.initials: DM
authors.lastname: Dunn
authors.affiliation: Department of Urology, State University of New York Upstate Medical University, Syracuse, NY 13210; Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, NY 13210; Cancer Research Institute, State University of New York Upstate Medical University, Syracuse, NY 13210.
authors.forename: Mark R
authors.initials: MR
authors.lastname: Woodford
authors.affiliation: Institute of Structural and Molecular Biology, Biological Sciences, University College London and Birkbeck College, London WC1E 7HX, United Kingdom;
authors.forename: Laura
authors.initials: L
authors.lastname: Mariotti
authors.affiliation: Department of Urology, State University of New York Upstate Medical University, Syracuse, NY 13210; Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, NY 13210; Cancer Research Institute, State University of New York Upstate Medical University, Syracuse, NY 13210.
authors.forename: Jacqualyn
authors.initials: J
authors.lastname: Schulman
authors.affiliation: Department of Urology, State University of New York Upstate Medical University, Syracuse, NY 13210; Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, NY 13210; Cancer Research Institute, State University of New York Upstate Medical University, Syracuse, NY 13210.
authors.forename: Dimitra
authors.initials: D
authors.lastname: Bourboulia
authors.affiliation: Department of Urology, State University of New York Upstate Medical University, Syracuse, NY 13210; Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, NY 13210; Cancer Research Institute, State University of New York Upstate Medical University, Syracuse, NY 13210.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Mollapour
authors.affiliation: Institute of Structural and Molecular Biology, Biological Sciences, University College London and Birkbeck College, London WC1E 7HX, United Kingdom; c.vaughan@mail.cryst.bbk.ac.uk.
authors.forename: Cara K
authors.identifier: 0000-0002-0220-730X
authors.initials: CK
authors.lastname: Vaughan
mesh_terms: D020134:Catalytic Domain; D018797:Cell Cycle Proteins / Q000737:chemistry; D018833:Chaperonins / Q000737:chemistry; D003460:Crystallization; D018841:HSP90 Heat-Shock Proteins / Q000502:physiology; D009687:Nuclear Proteins / Q000737:chemistry* / Q000502:physiology; D010749:Phosphoprotein Phosphatases / Q000737:chemistry* / Q000502:physiology; D010766:Phosphorylation; D013379:Substrate Specificity
chemical_list: C498362:CDC37 protein, human; D018797:Cell Cycle Proteins; D018841:HSP90 Heat-Shock Proteins; D009687:Nuclear Proteins; D010749:Phosphoprotein Phosphatases; C089641:protein phosphatase 5; D018833:Chaperonins
keywords: Cdc37; Hsp90; PP5; chaperone; phosphatase