title: S-Glutathionylation regulates HDL-associated paraoxonase 1 (PON1) activity.
abstract: HDL-associated paraoxonase 1 (PON1) undergoes inactivation under oxidative stress and is preserved by dietary antioxidants. PON1 cysteines can affect PON1 enzymatic activities. S-Glutathionylation, a redox regulatory mechanism characterized by the formation of a mixed disulfide between a protein thiol and oxidized glutathione (GSSG), was shown to preserve some enzymes from irreversible inactivation under pathological conditions. We questioned whether PON1 activity is regulated by S-glutathionylation. Incubation of PON1 or HDL with GSSG indeed resulted in a dose-dependent inactivation of PON1 activities, including its physiological activity to increase HDL-mediated macrophage cholesterol efflux. This PON1 inactivation was associated with the formation of a mixed disulfide bond between GSSG and PON1's cysteine residue(s), as detected by immunoblotting with anti-glutathione IgG. PON1 activity was recovered following the addition of a reducing agent, DL-Dithiothreitol (DTT), to the PON1-SSG complex. We thus conclude that HDL-associated serum PON1 can undergo S-glutathionylation under oxidative stress with a consequent reversible inactivation.
authors.affiliation: The Lipid Research Laboratory, The Technion Faculty of Medicine, The Rappaport Family Institute for Research in the Medical Sciences and Rambam Medical Center, 31096 Haifa, Israel.
authors.forename: Orit
authors.initials: O
authors.lastname: Rozenberg
authors.forename: Michael
authors.initials: M
authors.lastname: Aviram
mesh_terms: D000818:Animals; D043303:Aryldialkylphosphatase / Q000378:metabolism*; D002460:Cell Line; D002784:Cholesterol / Q000378:metabolism; D003545:Cysteine / Q000378:metabolism; D004229:Dithiothreitol / Q000494:pharmacology; D004789:Enzyme Activation; D005978:Glutathione / Q000378:metabolism*; D019803:Glutathione Disulfide / Q000378:metabolism; D008075:Lipoproteins, HDL / Q000378:metabolism*; D008264:Macrophages / Q000201:enzymology; D051379:Mice; D010084:Oxidation-Reduction; D019163:Reducing Agents / Q000494:pharmacology
chemical_list: D008075:Lipoproteins, HDL; D019163:Reducing Agents; D002784:Cholesterol; D043303:Aryldialkylphosphatase; D005978:Glutathione; D003545:Cysteine; D004229:Dithiothreitol; D019803:Glutathione Disulfide