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Nucleotide excision repair is more complex in eukaryotes than prokaryotes, which express enzymes like the photolyase. In humans and other placental animals , there are 9 major proteins involved in NER.
During nucleotide excision repair, several protein complexes cooperate to recognize damaged DNA and locally separate the DNA helix for a short distance on either side of the site of a site of DNA damage. The ERCC1–XPF nuclease incises the damaged DNA strand on the 5′ side of the lesion. [14]
In general global response to DNA damage involves expression of multiple genes responsible for postreplication repair, homologous recombination, nucleotide excision repair, DNA damage checkpoint, global transcriptional activation, genes controlling mRNA decay, and many others. A large amount of damage to a cell leaves it with an important ...
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]
Mismatch repair is a highly conserved process from prokaryotes to eukaryotes. The first evidence for mismatch repair was obtained from S. pneumoniae (the hexA and hexB genes ). Subsequent work on E. coli has identified a number of genes that, when mutationally inactivated, cause hypermutable strains.
Thus the first SOS repair mechanism to be induced is nucleotide excision repair (NER), whose aim is to fix DNA damage without commitment to a full-fledged SOS response. If, however, NER does not suffice to fix the damage, the LexA concentration is further reduced, so the expression of genes with stronger LexA boxes (such as sulA , umuD , umuC ...
The complex of XPC-RAD23B is the initial damage recognition factor in global genomic nucleotide excision repair (GG-NER). XPC-RAD23B recognizes a wide variety of lesions that thermodynamically destabilize DNA duplexes, including UV-induced photoproducts (cyclopyrimidine dimers and 6-4 photoproducts ), adducts formed by environmental mutagens such as benzo[a]pyrene or various aromatic amines ...
DNA can be damaged by ultraviolet radiation, toxins, radioactive substances, and reactive biochemical intermediates like free radicals.The ERCC6 protein is involved in repairing the genome when specific genes undergoing transcription (dubbed active genes) are inoperative; as such, ERCC6 serves as a transcription-coupled excision repair protein, being one of the fundamental enzymes in active ...