title: Assembly and quality control of the protein phosphatase 1 holoenzyme involves the Cdc48-Shp1 chaperone.
abstract: Protein phosphatase 1 (PP1) controls many aspects of cell physiology, which depends on its correct targeting in the cell. Nuclear localization of Glc7, the catalytic subunit of PP1 in budding yeast, requires the AAA-ATPase Cdc48 and its adaptor Shp1 through an unknown mechanism. Herein, we show that mutations in SHP1 cause misfolding of Glc7 that co-aggregates with Hsp104 and Hsp42 chaperones and requires the proteasome for clearance. Mutation or depletion of the PP1 regulatory subunits Sds22 and Ypi1, which are involved in nuclear targeting of Glc7, also produce Glc7 aggregates, indicating that association with regulatory subunits stabilizes Glc7 conformation. Use of a substrate-trap Cdc48(QQ) mutant reveals that Glc7-Sds22-Ypi1 transiently associates with and is the major target of Cdc48-Shp1. Furthermore, Cdc48-Shp1 binds and prevents misfolding of PP1-like phosphatases Ppz2 and Ppq1, but not other types of phosphatases. Our data suggest that Cdc48-Shp1 functions as a molecular chaperone for the structural integrity of PP1 complex in general and that it specifically promotes the assembly of Glc7-Sds22-Ypi1 for nuclear import.
authors.affiliation: Graduate Institute of Life Sciences, National Defense Medical Center, Taipei 114, Taiwan.
authors.forename: You-Liang
authors.initials: YL
authors.lastname: Cheng
authors.affiliation: Graduate Institute of Life Sciences, National Defense Medical Center, Taipei 114, Taiwan Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan reyhuei@gate.sinica.edu.tw.
authors.forename: Rey-Huei
authors.initials: RH
authors.lastname: Chen
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000378:metabolism*; D047468:Immunoprecipitation; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D013058:Mass Spectrometry; D018832:Molecular Chaperones / Q000378:metabolism*; D017510:Protein Folding; D054645:Protein Phosphatase 1 / Q000737:chemistry / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000254:growth & development / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D000074405:Valosin Containing Protein
chemical_list: D018797:Cell Cycle Proteins; D047908:Intracellular Signaling Peptides and Proteins; D018832:Molecular Chaperones; C106691:SHP1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C480163:Ypi1 protein, S cerevisiae; C092048:GLC7 protein, S cerevisiae; D054645:Protein Phosphatase 1; D000251:Adenosine Triphosphatases; C000614177:CDC48 protein, S cerevisiae; D000074405:Valosin Containing Protein
keywords: Cdc48; Chaperone; Protein folding; Protein phosphatase 1; Shp1