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Hyperacetylation of SOD2 Mediates Transporting Its Cytosolic Precursor into Mitochondrial Matrix in the Murine Heart of SOD2‐tg
Author(s) -
Chen YeongRenn,
Zhang Liwen,
Chen ChwenLih,
Kang Patrick
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.955.8
Subject(s) - sod2 , acetylation , mitochondrial matrix , mitochondrion , chemistry , cytosol , microbiology and biotechnology , superoxide dismutase , biochemistry , biology , oxidative stress , enzyme , gene
SOD2 is the primary enzyme that neutralizes • O 2 ‐ to H 2 O 2 in mitochondria. Cardiac‐specific SOD2 overexpression (SOD2‐tg mouse) induces supernormal function and physiological hypertrophy in mouse heart. However, the stress imposed by SOD2 overexpression also resulted in protein aggregation of SOD2 and SOD2 hyperacetylation marked in mitochondria, which is associated with the phenotype of hypertrophy. We studied SOD2 acetylation from SOD2‐tg murine heart. We found acetylation of mature SOD2 and its precursor were detected in the mitochondrial matrix and cytosol by immunoblotting using the acetyllysine antibody. LC/MS/MS analysis indicated that K 68 , K 122 , K 130 , and K 202 of mature SOD2 in matrix were acetylated. LC/MS/MS analysis further revealed that K 68 , K 75 , K 89 , K 114 , K 122 , K 130 , K 132 , K 134 , K 154 , and K 202 of cytosolic SOD2 precursor were acetylated except residues of K 194 , K 202 , K 221 and K 222 at the C‐terminus. The results indicated that transport of SOD2 precursor into mitochondrial matrix resulted in Sirt 3‐mediated deacetylation at the residues of K 75 , K 89 , K 114 , K 132 , K 134 , K 154 ; and site‐specific acetylation at K 202 . In vitro acetylation of mature SOD2 with acetic anhydride deaggregated pentameric SOD2, restored the profile of hyperacetylation observed in the cytosolic SOD2 precursor, and subsequently decreased the enzymatic activity of SOD2 as measured by EPR. The results concludes protein hyperacetylation of SOD2 inactivates the cytosolic precursor, and mediates transporting SOD2 into mitochondrial matrix, subsequently activating mature SOD2 via Sirt 3‐mediated deacetylation.