Acetylation of oxidized base repair-initiating NEIL1 DNA glycosylase required for chromatin-bound repair complex formation in the human genome increases cellular resistance to oxidative stress

Abstract

Posttranslational modifications of DNA repair proteins have been linked to their function. However, it is not clear if posttranslational acetylation affects subcellular localization of these enzymes. Here, we show that the human DNA glycosylase NEIL1, which is involved in repair of both endo- and exogenously generated oxidized bases via the base excision repair (BER) pathway, is acetylated by histone acetyltransferase p300. Acetylation occurs predominantly at Lys residues 296, 297 and 298 located in NEIL1's disordered C-terminal domain. NEIL1 mutant having the substitution of Lys 296-298 with neutral Ala loses nuclear localization, whereas Lys > Arg substitution (in 3KR mutant) at the same sites does not affect NEIL1's nuclear localization or chromatin binding, presumably due to retention of the positive charge. Although non-acetylated NEIL1 can bind to chromatin, acetylated NEIL1 is exclusively chromatin-bound. NEIL1 acetylation while dispensable for its glycosylase activity enhances it due to increased product release. The acetylation-defective 3KR mutant forms less stable complexes with various chromatin proteins, including histone chaperones and BER/single-strand break repair partners, than the wild-type (WT) NEIL1. We also showed that the repair complex with WT NEIL1 has significantly higher BER activity than the 3KR mutant complex. This is consistent with reduced resistance of non-acetylable mutant NEIL1 expressing cells to oxidative stress relative to cells expressing the acetylable WT enzyme. We thus conclude that the major role of acetylable Lys residues in NEIL1 is to stabilize the formation of chromatin-bound repair complexes which protect cells from oxidative stress.

Mutation accumulation in cancer genes relates to nonoptimal outcome in chronic myeloid leukemia

“…These analyses revealed deregulation of genes reported to be altered in previous CML investigations, such as RXFP1, 43 PIEZO2, 55 and CD26, 56 and in leukemia studies, such as CD69, 57 ST18, 58 and MUC4. 59 Expression analysis also suggested that DNA damage could be related to the downregulation of DNA-repair machinery genes and that dysregulation events in genes, including DNMT1, 60 SEPP1, 61 NEIL1, 62 and WT1, 63,64 may have contributed to the high occurrence of DNA damage-associated variants in our cohort. In addition, several immune checkpoint genes were found to be deregulated, suggesting an explanation for how CML cells evade immune-cell clearance.…”

Niacin Inhibits Apoptosis and Rescues Premature Ovarian Failure

“…Because acetylation covalently modifies many proteins, it has strong chromatin-modifying potential in DNA repair, transcription and replication. Some evidence has suggested that histone deacetylase (HDAC) inhibitors exert neuroprotective effects against various insults and deficits in the central nervous system [28,29], and some protein acetylation can help cell survive and resist to oxidative stress [30].…”

Ligand-induced gene activation is associated with oxidative genome damage whose repair is required for transcription

“…We speculated that to efficiently coordinate histone/CpG demethylation and repair of the demethylation-induced genome damage, the demethylases and BER/SSBR proteins colocalize in chromatin-bound preformed complexes. We extensively characterized chromatin-bound multiprotein complexes that contained BER/SSBR proteins, along with nonrepair proteins; furthermore, we showed that these complexes were competent in repairing the oxidized bases ( 33 – 36 ). Exposure to ROS increased the stability of these unique complexes, which were distinct for various BER subpathways ( 23 , 34 , 35 , 37 ).…”