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Epigenetic alterations can accompany DNA repair of oxidative damage or double-strand breaks. In human cells, oxidative DNA damage occurs about 10,000 times a day and DNA double-strand breaks occur about 10 to 50 times a cell cycle in somatic replicating cells (see DNA damage (naturally occurring)). The selective advantage of DNA repair is to ...
XthA (exonuclease III, a DNA repair enzyme) and KatE (catalase) are known to play important roles in the defense against oxidative stress but KatF regulon genes are not induced by oxidative stress. [2] There is an overlap between oxidative stress response and other regulatory networks like heat shock response, SOS response.
The SOS system has enhanced DNA-repair capacity, including excision and post-replication repair, enhanced mutagenesis and prophage induction. The system can also inhibit cell division and cell respiration. [1] The SOS response has been proposed as a model for bacterial evolution of certain types of antibiotic resistance. [2]
DNA oxidation is the process of oxidative damage of deoxyribonucleic acid.As described in detail by Burrows et al., [1] 8-oxo-2'-deoxyguanosine (8-oxo-dG) is the most common oxidative lesion observed in duplex DNA because guanine has a lower one-electron reduction potential than the other nucleosides in DNA.
More than 100 types of oxidative DNA damage have been characterized, and 8-oxodG constitutes about 5% of the steady state oxidative damages in DNA. [18] Helbock et al. [ 14 ] estimated that there were 24,000 steady state oxidative DNA adducts per cell in young rats and 66,000 adducts per cell in old rats.
The adaptive response is a DNA damage response pathway prevalent across bacteria that protects DNA from damage by external agents or by errors during replication. [1] [2] It is initiated specifically against alkylation, particularly methylation, of guanine or thymine nucleotides or phosphate groups on the sugar-phosphate backbone of DNA.
UvrABC endonuclease is a multienzyme complex in bacteria involved in DNA repair by nucleotide excision repair, and it is, therefore, sometimes called an excinuclease.This UvrABC repair process, sometimes called the short-patch process, involves the removal of twelve nucleotides where a genetic mutation has occurred followed by a DNA polymerase, replacing these aberrant nucleotides with the ...
Steady-state levels of DNA damages represent the balance between formation and repair. Swenberg et al. [3] measured average frequencies of steady state endogenous DNA damages in mammalian cells. The most frequent oxidative DNA damage normally present in DNA is 8-oxo-dG, occurring at an average frequency of 2,400 per cell.