title: Selective activators of protein phosphatase 5 target the auto-inhibitory mechanism.
abstract: Protein phosphatase 5 (PP5) is an evolutionary conserved serine/threonine phosphatase. Its dephosphorylation activity modulates a diverse set of cellular factors including protein kinases and the microtubule-associated tau protein involved in neurodegenerative disorders. It is auto-regulated by its heat-shock protein (Hsp90)-interacting tetratricopeptide repeat (TPR) domain and its C-terminal α-helix. In the present study, we report the identification of five specific PP5 activators [PP5 small-molecule activators (P5SAs)] that enhance the phosphatase activity up to 8-fold. The compounds are allosteric modulators accelerating efficiently the turnover rate of PP5, but do barely affect substrate binding or the interaction between PP5 and the chaperone Hsp90. Enzymatic studies imply that the compounds bind to the phosphatase domain of PP5. For the most promising compound crystallographic comparisons of the apo PP5 and the PP5-P5SA-2 complex indicate a relaxation of the auto-inhibited state of PP5. Residual electron density and mutation analyses in PP5 suggest activator binding to a pocket in the phosphatase/TPR domain interface, which may exert regulatory functions. These compounds thus may expose regulatory mechanisms in the PP5 enzyme and serve to develop optimized activators based on these scaffolds.
authors.affiliation: Department of Chemistry, Center for Integrated Protein Science, Technische Universität München, 85748 Garching, Germany.
authors.forename: Veronika
authors.initials: V
authors.lastname: Haslbeck
authors.affiliation: Department of Chemistry, Center for Integrated Protein Science, Technische Universität München, 85748 Garching, Germany.
authors.forename: Adrian
authors.initials: A
authors.lastname: Drazic
authors.affiliation: Department of Chemistry, Center for Integrated Protein Science, Technische Universität München, 85748 Garching, Germany.
authors.forename: Julia M
authors.initials: JM
authors.lastname: Eckl
authors.affiliation: Department of Chemistry, Center for Integrated Protein Science, Technische Universität München, 85748 Garching, Germany.
authors.forename: Ferdinand
authors.initials: F
authors.lastname: Alte
authors.affiliation: AG Neurodegeneration and Intervention Strategies, German Center for Neurodegenerative Diseases, 39120 Magdeburg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Helmuth
authors.affiliation: Department of Chemistry, Center for Integrated Protein Science, Technische Universität München, 85748 Garching, Germany Institute of Structural Biology, Helmholtz Zentrum München, 85764 Neuherberg, Germany.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Popowicz
authors.affiliation: Institute of Structural Biology, Helmholtz Zentrum München, 85764 Neuherberg, Germany.
authors.forename: Werner
authors.initials: W
authors.lastname: Schmidt
authors.affiliation: Department of Chemistry, Center for Integrated Protein Science, Technische Universität München, 85748 Garching, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Braun
authors.affiliation: Max Planck Research Unit for Enzymology of Protein Folding, 06120 Halle (Saale), Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Weiwad
authors.affiliation: Max Planck Research Unit for Enzymology of Protein Folding, 06120 Halle (Saale), Germany.
authors.forename: Gunter
authors.initials: G
authors.lastname: Fischer
authors.affiliation: Department of Chemistry, Center for Integrated Protein Science, Technische Universität München, 85748 Garching, Germany.
authors.forename: Gerd
authors.initials: G
authors.lastname: Gemmecker
authors.affiliation: Department of Chemistry, Center for Integrated Protein Science, Technische Universität München, 85748 Garching, Germany Institute of Structural Biology, Helmholtz Zentrum München, 85764 Neuherberg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Sattler
authors.affiliation: AG Neurodegeneration and Intervention Strategies, German Center for Neurodegenerative Diseases, 39120 Magdeburg, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Striggow
authors.affiliation: Department of Chemistry, Center for Integrated Protein Science, Technische Universität München, 85748 Garching, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Groll
authors.affiliation: Department of Chemistry, Center for Integrated Protein Science, Technische Universität München, 85748 Garching, Germany klaus.richter@richterlab.de.
authors.forename: Klaus
authors.initials: K
authors.lastname: Richter
mesh_terms: D000818:Animals; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism; D018360:Crystallography, X-Ray; D004353:Drug Evaluation, Preclinical / Q000379:methods; D004789:Enzyme Activation / Q000187:drug effects; D050883:HSC70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D019906:Nuclear Magnetic Resonance, Biomolecular; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D000072417:Protein Domains; D051381:Rats; D054852:Small Molecule Libraries / Q000494:pharmacology*
chemical_list: D029742:Caenorhabditis elegans Proteins; D050883:HSC70 Heat-Shock Proteins; D009687:Nuclear Proteins; D054852:Small Molecule Libraries; D010749:Phosphoprotein Phosphatases; C089641:protein phosphatase 5
keywords: modulation of phosphatase activity; protein phosphatase 5; small-molecular activators