http://www.jbc.org/content/290/23/14610.full Above is link. please serch by abov
ID: 196823 • Letter: H
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http://www.jbc.org/content/290/23/14610.full
Above is link. please serch by above link. Copy and paste on the google and it will show you article.
Talhaoui, I., Shafirovich, V., Liu, Z., Saint-Pierre, C., Akishev, Z., Matkarimov, B.T., Gasparutto, D., Geacintov, N.E., and M. Saparbaev. (2015). Oxidatively Generated Guanine (C8)-Thymine(N3) Intrastrand Cross-links in Double-stranded DNA are Repaired by Base Excision Repair Pathways. Journal of Biological Chemistry, 290: 14610
What hypothesis do the authors propose?
Describe the DNA damage that occurs in human cells as a result of oxidative damage?
How did the authors determine that base excision repair corrected errors from oxidative damage?
What did the authors conclude about BER and NER repair systems?
Explanation / Answer
1. Hypothesis proposed by authors : Base excision repair (BER) is the major pathway for repair of single oxidized nucleobases.
2. Oxidative damage due to reactive oxygen intermediates causes the intrastand and interstand cross linked Lesions in DNA helix. These are difficult to remove by DNA repair mechanism.These lesions are as result of covalent coupling of two nucleotides on opposite DNA strands, while the coupling of two nucleotides on the same strand gives rise to intrastrand cross-linked (IntraCL) lesions.
3. Base excision repair corrected errors from oxidative damage: The authorv has investigated various eukaryotic and prokaryotic bifunctional DNA glycosylases/lyases and PAGE and MALDI-TOF/MS show that the G*[C8-N3]T* lesions in 17-mer duplexes are incised on either side of G* and no fragment is recoveredc with G*, simultaneously T* is converted to a normal T in the 3-fragment cleavage products. This capability of DNA glycosylases to incise the DNA strand adjacent to G* indicates the versatility of these base excision repair proteins.
4. The author concluded that 8,5-cyclo-2-deoxypurine lesions are not repaired by DNA glycosylase-mediated BER mechanisms, but are excellent substrates of mammalian NER and prokaryotic NER repair pathways.And both BER and NER can function in parallel in incising the G*T* and G*CT* intrastrand cross-links in DNA.
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