Nucleolar accumulation of APE1 depends on charged lysine residues that undergo acetylation upon genotoxic stress and modulate its BER activity in cells.
Apurinic/apyrimidinic endonuclease 1 (APE1) is the main abasic endonuclease in the base excision repair (BER) pathway of DNA lesions caused by oxidation/alkylation in mammalian cells; within nucleoli it interacts with nucleophosmin and rRNA through N-terminal Lys residues, some of which (K(27)/K(31)/K(32)/K(35)) may undergo acetylation in vivo. Here we study the functional role of these modifications during genotoxic damage and their in vivo relevance. We demonstrate that cells expressing a specific K-to-A multiple mutant are APE1 nucleolar deficient and are more resistant to genotoxic treatment than those expressing the wild type, although they show impaired proliferation. Of interest, we find that genotoxic treatment induces acetylation at these K residues. We also find that the charged status of K(27)/K(31)/K(32)/K(35) modulates acetylation at K(6)/K(7) residues that are known to be involved in the coordination of BER activity through a mechanism regulated by the sirtuin 1 deacetylase. Of note, structural studies show that acetylation at K(27)/K(31)/K(32)/K(35) may account for local conformational changes on APE1 protein structure. These results highlight the emerging role of acetylation of critical Lys residues in regulating APE1 functions. They also suggest the existence of cross-talk between different Lys residues of APE1 occurring upon genotoxic damage, which may modulate APE1 subnuclear distribution and enzymatic activity in vivo.
Department of Medical and Biological Sciences, University of Udine, 33100 Udine, Italy.
Lisa
L
Lirussi
Giulia
G
Antoniali
Carlo
C
Vascotto
Chiara
C
D'Ambrosio
Mattia
M
Poletto
Milena
M
Romanello
Daniela
D
Marasco
Marilisa
M
Leone
Franco
F
Quadrifoglio
Kishor K
KK
Bhakat
Andrea
A
Scaloni
Gianluca
G
Tell
D000107:Acetylation; D002466:Cell Nucleolus / Q000201:enzymology*; D049109:Cell Proliferation; D004249:DNA Damage; D004260:DNA Repair; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000737:chemistry* / Q000378:metabolism*; D004795:Enzyme Stability; D006367:HeLa Cells; D006801:Humans; D008239:Lysine / Q000378:metabolism*; D050505:Mutant Proteins / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D000090243:Nucleophosmin; D011485:Protein Binding; D011487:Protein Conformation; D021381:Protein Transport; D012335:RNA, Ribosomal / Q000378:metabolism; D056564:Sirtuin 1 / Q000378:metabolism; D013329:Structure-Activity Relationship
D050505:Mutant Proteins; C000716967:NPM1 protein, human; D009687:Nuclear Proteins; D012335:RNA, Ribosomal; D000090243:Nucleophosmin; C447939:SIRT1 protein, human; D056564:Sirtuin 1; C085108:APEX1 protein, human; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D008239:Lysine