Sirt3-mediated deacetylation of evolutionarily conserved lysine 122 regulates MnSOD activity in response to stress

Mol Cell. 2010 Dec 22;40(6):893-904. doi: 10.1016/j.molcel.2010.12.013.


Genetic deletion of the mitochondrial deacetylase sirtuin-3 (Sirt3) results in increased mitochondrial superoxide, a tumor-permissive environment, and mammary tumor development. MnSOD contains a nutrient- and ionizing radiation (IR)-dependent reversible acetyl-lysine that is hyperacetylated in Sirt3⁻/⁻ livers at 3 months of age. Livers of Sirt3⁻/⁻ mice exhibit decreased MnSOD activity, but not immunoreactive protein, relative to wild-type livers. Reintroduction of wild-type but not deacetylation null Sirt3 into Sirt3⁻/⁻ MEFs deacetylated lysine and restored MnSOD activity. Site-directed mutagenesis of MnSOD lysine 122 to an arginine, mimicking deacetylation (lenti-MnSOD(K122-R)), increased MnSOD activity when expressed in MnSOD⁻/⁻ MEFs, suggesting acetylation directly regulates function. Furthermore, infection of Sirt3⁻/⁻ MEFs with lenti-MnSOD(K122-R) inhibited in vitro immortalization by an oncogene (Ras), inhibited IR-induced genomic instability, and decreased mitochondrial superoxide. Finally, IR was unable to induce MnSOD deacetylation or activity in Sirt3⁻/⁻ livers, and these irradiated livers displayed significant IR-induced cell damage and microvacuolization in their hepatocytes.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Acetylation
  • Animals
  • Arginine / metabolism
  • Cell Line
  • Conserved Sequence*
  • Evolution, Molecular*
  • Lysine / metabolism*
  • Mice
  • Mutagenesis, Site-Directed
  • Oxidative Stress*
  • Sirtuin 3 / deficiency
  • Sirtuin 3 / genetics
  • Sirtuin 3 / metabolism*
  • Superoxide Dismutase / metabolism*


  • Sirt3 protein, mouse
  • Arginine
  • Superoxide Dismutase
  • Sirtuin 3
  • Lysine