title: Protein s-glutathionylation in retinal pigment epithelium converts heat shock protein 70 to an active chaperone.
abstract: A disulfide bond between key redox-sensitive cysteine residues and glutathione is one mechanism by which redox related allosteric effectors can regulate protein structure and function. Here we test the hypothesis that glutaredoxin-1 (Grx-1), a member of the oxidoreductase family of enzymes, may be a critical component of redox-sensitive molecular switches by mediating reversible protein S-glutathionylation and enzymatic catalysis of thiol/disulfide exchange. Deglutathionylation of a 70 kDa protein by Grx-1 was detected using a monoclonal antibody specific to protein S-glutathionylation. Heat shock cognate protein 70 (Hsc70) was identified as a substrate of Grx-1 through mass spectrometry. Recombinant Hsc70 was glutathionylated in vitro, and protein S-glutathionylation reversed by Grx-1. Glutathionylated Hsc70 was more effective in preventing luciferase aggregation at 43 degrees C than reduced Hsc70 in a dose dependent fashion. ATP did not effect the chaperone activity of Hsc70-SG but did increase the activity of reduced Hsc70-SG. Reversible glutathionylation of Hsc70 may provide a mechanism for post-translation regulation of chaperone activity.
authors.affiliation: Cole Eye Institute, Lerner Research Institute, Cleveland Clinic, Foundation, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
authors.forename: George
authors.initials: G
authors.lastname: Hoppe
authors.forename: Yuh-Cherng
authors.initials: YC
authors.lastname: Chai
authors.forename: John W
authors.initials: JW
authors.lastname: Crabb
authors.forename: Jonathan
authors.initials: J
authors.lastname: Sears
mesh_terms: D000595:Amino Acid Sequence; D002478:Cells, Cultured; D054477:Glutaredoxins; D005978:Glutathione / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D018832:Molecular Chaperones / Q000378:metabolism; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000502:physiology; D010088:Oxidoreductases; D010857:Pigment Epithelium of Eye / Q000378:metabolism*; D011506:Proteins / Q000235:genetics / Q000494:pharmacology / Q000502:physiology; D011994:Recombinant Proteins / Q000494:pharmacology
chemical_list: C516005:GLRX protein, human; D054477:Glutaredoxins; D018840:HSP70 Heat-Shock Proteins; D018832:Molecular Chaperones; D011506:Proteins; D011994:Recombinant Proteins; D010088:Oxidoreductases; D005978:Glutathione