Rozenberg Orit, Aviram Michael
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.
Biochem Biophys Res Commun. 2006 Dec 15;351(2):492-8. doi: 10.1016/j.bbrc.2006.10.059. Epub 2006 Oct 18.
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.
高密度脂蛋白相关的对氧磷酶1（PON1）在氧化应激下会失活，而膳食抗氧化剂可使其得以保留。PON1中的半胱氨酸会影响其酶活性。S-谷胱甘肽化是一种氧化还原调节机制，其特征是在蛋白质硫醇与氧化型谷胱甘肽（GSSG）之间形成混合二硫键，研究表明这种机制可使一些酶在病理条件下免于不可逆失活。我们质疑PON1的活性是否受S-谷胱甘肽化调节。用GSSG孵育PON1或高密度脂蛋白确实导致PON1活性呈剂量依赖性失活，包括其促进高密度脂蛋白介导的巨噬细胞胆固醇外流的生理活性。通过用抗谷胱甘肽IgG进行免疫印迹检测发现，这种PON1失活与GSSG和PON1的半胱氨酸残基之间形成混合二硫键有关。向PON1-SSG复合物中加入还原剂二硫苏糖醇（DTT）后，PON1活性得以恢复。因此我们得出结论，在氧化应激下，高密度脂蛋白相关的血清PON1会发生S-谷胱甘肽化，从而导致可逆性失活。
