Reading Targeted DNA Damage in the Active Demethylation Pathway: Role of Accessory Domains of Eukaryotic AP Endonucleases and Thymine-DNA Glycosylases.

Base excision DNA repair (BER) is an important process used by all living organisms to remove nonbulky lesions from DNA. BER is usually initiated by DNA glycosylases that excise a damaged base leaving an apurinic/apyrimidinic (AP) site, and an AP endonuclease then cuts DNA at the AP site, and the repair is completed by correct nucleotide insertion, end processing, and nick ligation. It has emerged recently that the BER machinery, in addition to genome protection, is crucial for active epigenetic demethylation in the vertebrates.

Variable termination sites of DNA polymerases encountering a DNA-protein cross-link.

DNA-protein cross-links (DPCs) are important DNA lesions induced by endogenous crosslinking agents such as formaldehyde or acetaldehyde, as well as ionizing radiation, cancer chemotherapeutic drugs, and abortive action of some enzymes. Due to their very bulky nature, they are expected to interfere with DNA and RNA synthesis and DNA repair. DPCs are highly genotoxic and the ability of cells to deal with them is relevant for many chemotherapeutic interventions.