title: The protein targeting factor Get3 functions as ATP-independent chaperone under oxidative stress conditions.
abstract: Exposure of cells to reactive oxygen species (ROS) causes a rapid and significant drop in intracellular ATP levels. This energy depletion negatively affects ATP-dependent chaperone systems, making ROS-mediated protein unfolding and aggregation a potentially very challenging problem. Here we show that Get3, a protein involved in ATP-dependent targeting of tail-anchored (TA) proteins under nonstress conditions, turns into an effective ATP-independent chaperone when oxidized. Activation of Get3's chaperone function, which is a fully reversible process, involves disulfide bond formation, metal release, and its conversion into distinct, higher oligomeric structures. Mutational studies demonstrate that the chaperone activity of Get3 is functionally distinct from and likely mutually exclusive with its targeting function, and responsible for the oxidative stress-sensitive phenotype that has long been noted for yeast cells lacking functional Get3. These results provide convincing evidence that Get3 functions as a redox-regulated chaperone, effectively protecting eukaryotic cells against oxidative protein damage.
authors.affiliation: Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA; Department of Molecular Biology, Universitätsmedizin Göttingen, 37073 Göttingen, Germany.
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Voth
authors.affiliation: Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Markus
authors.initials: M
authors.lastname: Schick
authors.affiliation: Department of Biological Chemistry, Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Gates
authors.affiliation: Department of Medicine, University of California San Diego School of Medicine, San Diego, CA 92093, USA.
authors.forename: Sheng
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Molecular Biology, Universitätsmedizin Göttingen, 37073 Göttingen, Germany.
authors.forename: Fabio
authors.initials: F
authors.lastname: Vilardi
authors.affiliation: Department of Molecular Biology, Universitätsmedizin Göttingen, 37073 Göttingen, Germany; Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK.
authors.forename: Irina
authors.initials: I
authors.lastname: Gostimskaya
authors.affiliation: Department of Biological Chemistry, Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Southworth
authors.affiliation: Department of Molecular Biology, Universitätsmedizin Göttingen, 37073 Göttingen, Germany; Max-Planck Institut for Biophysical Chemistry, 37077 Göttingen, Germany. Electronic address: blanche.schwappach@med.uni-goettingen.de.
authors.forename: Blanche
authors.initials: B
authors.lastname: Schwappach
authors.affiliation: Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA. Electronic address: ujakob@umich.edu.
authors.forename: Ursula
authors.initials: U
authors.lastname: Jakob
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D000255:Adenosine Triphosphate / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D008954:Models, Biological; D018832:Molecular Chaperones / Q000378:metabolism / Q000502:physiology; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D058767:Protein Unfolding; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*
chemical_list: D020662:Guanine Nucleotide Exchange Factors; D018832:Molecular Chaperones; D029701:Saccharomyces cerevisiae Proteins; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; C529048:Get3 protein, S cerevisiae