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Basic steps of base excision repair. Base excision repair (BER) is a cellular mechanism, studied in the fields of biochemistry and genetics, that repairs damaged DNA throughout the cell cycle. It is responsible primarily for removing small, non-helix-distorting base lesions from the genome. The related nucleotide excision repair pathway repairs
Several review articles have shown that deficient DNA repair, allowing greater accumulation of DNA damage, causes premature aging; and that increased DNA repair facilitates greater longevity, e.g. [5] [6] Mouse models of nucleotide-excision–repair syndromes reveal a striking correlation between the degree to which specific DNA repair pathways ...
Enzymes, namely DNA glycosylases, also commonly create AP sites, as part of the base excision repair pathway. In a given mammalian cell, 5000–10,000 apurinic sites are estimated to form per day. Apyrimidinic sites form at a rate roughly 20 times slower, with estimates at around 500 formation events per day, per cell.
Most of the DNA repair deficiency diseases show varying degrees of "accelerated aging" or cancer (often some of both). [37] But elimination of any gene essential for base excision repair kills the embryo—it is too lethal to display symptoms (much less symptoms of cancer or "accelerated aging"). [38]
XPC, upon ubiquitination, is activated and initiates the nucleotide excision repair pathway. Somewhat later, at 30 minutes after UV damage, the INO80 chromatin remodeling complex is recruited to the site of the DNA damage, and this coincides with the binding of further nucleotide excision repair proteins, including ERCC1. [67]
Apurinic/apyrimidinic (AP) endonuclease is an enzyme that is involved in the DNA base excision repair pathway (BER). Its main role in the repair of damaged or mismatched nucleotides in DNA is to create a nick in the phosphodiester backbone of the AP site created when DNA glycosylase removes the damaged base.
Uracil-DNA glycosylases are DNA repair enzymes that excise uracil residues from DNA by cleaving the N-glycosydic bond, initiating the base excision repair pathway. Uracil in DNA can arise either through the deamination of cytosine to form mutagenic U:G mispairs, or through the incorporation of dUMP by DNA polymerase to form U:A pairs. [18]
The protein encoded by this gene is one of two human homologs of Saccharomyces cerevisiae Rad23, a protein involved in nucleotide excision repair (NER). This protein was shown to interact with, and elevate the nucleotide excision activity of 3-methyladenine-DNA glycosylase (MPG), which suggested a role in DNA damage recognition in base excision repair.