title: Novel mechanisms for superoxide-scavenging activity of human manganese superoxide dismutase determined by the K68 key acetylation site.
abstract: Superoxide is the primary reactive oxygen species generated in the mitochondria. Manganese superoxide dismutase (SOD2) is the major enzymatic superoxide scavenger present in the mitochondrial matrix and one of the most crucial reactive oxygen species-scavenging enzymes in the cell. SOD2 is activated by sirtuin 3 (SIRT3) through NAD(+)-dependent deacetylation. However, the exact acetylation sites of SOD2 are ambiguous and the mechanisms underlying the deacetylation-mediated SOD2 activation largely remain unknown. We are the first to characterize SOD2 mutants of the acetylation sites by investigating the relative enzymatic activity, structures, and electrostatic potential of SOD2 in this study. These SOD2 mutations affected the superoxide-scavenging activity in vitro and in HEK293T cells. The lysine 68 (K68) site is the most important acetylation site contributing to SOD2 activation and plays a role in cell survival after paraquat treatment. The molecular basis underlying the regulation of SOD2 activity by K68 was investigated in detail. Molecular dynamics simulations revealed that K68 mutations induced a conformational shift of residues located in the active center of SOD2 and altered the charge distribution on the SOD2 surface. Thus, the entry of the superoxide anion into the coordinated core of SOD2 was inhibited. Our results provide a novel mechanistic insight, whereby SOD2 acetylation affects the structure and charge distribution of SOD2, its tetramerization, and p53-SOD2 interactions of SOD2 in the mitochondria, which may play a role in nuclear-mitochondrial communication during aging.
authors.affiliation: State Key Laboratory of Natural and Biomimetic Drugs, Department of Chemical Biology, School of Pharmaceutical Sciences, Peking University, Beijing, People׳s Republic of China.
authors.forename: Jiaqi
authors.initials: J
authors.lastname: Lu
authors.affiliation: State Key Laboratory of Natural and Biomimetic Drugs, Department of Chemical Biology, School of Pharmaceutical Sciences, Peking University, Beijing, People׳s Republic of China.
authors.forename: Kuoyuan
authors.initials: K
authors.lastname: Cheng
authors.affiliation: State Key Laboratory of Natural and Biomimetic Drugs, Department of Chemical Biology, School of Pharmaceutical Sciences, Peking University, Beijing, People׳s Republic of China.
authors.forename: Bo
authors.initials: B
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Natural and Biomimetic Drugs, Department of Chemical Biology, School of Pharmaceutical Sciences, Peking University, Beijing, People׳s Republic of China.
authors.forename: Huan
authors.initials: H
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Natural and Biomimetic Drugs, Department of Chemical Biology, School of Pharmaceutical Sciences, Peking University, Beijing, People׳s Republic of China.
authors.forename: Yuanzhao
authors.initials: Y
authors.lastname: Cao
authors.affiliation: State Key Laboratory of Natural and Biomimetic Drugs, Department of Chemical Biology, School of Pharmaceutical Sciences, Peking University, Beijing, People׳s Republic of China.
authors.forename: Fei
authors.initials: F
authors.lastname: Guo
authors.affiliation: Department of Medicine, Children׳s Hospital Boston, Harvard Medical School, Boston, MA 02445, USA. Electronic address: xudong.feng@childrens.harvard.edu.
authors.forename: Xudong
authors.initials: X
authors.lastname: Feng
authors.affiliation: State Key Laboratory of Natural and Biomimetic Drugs, Department of Chemical Biology, School of Pharmaceutical Sciences, Peking University, Beijing, People׳s Republic of China. Electronic address: xqing@hsc.pku.edu.cn.
authors.forename: Qing
authors.initials: Q
authors.lastname: Xia
mesh_terms: D000107:Acetylation; D000595:Amino Acid Sequence; D000818:Animals; D057809:HEK293 Cells; D006801:Humans; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D017386:Sequence Homology, Amino Acid; D013482:Superoxide Dismutase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism*
chemical_list: D013481:Superoxides; D013482:Superoxide Dismutase
keywords: Acetylation; Electrostatic potential; Mitochondria; ROS; Structure; Superoxide; Superoxide dismutase; Tetramerization