Publication Date:
2010-04-13
Description:
Mammalian cells require non-homologous end joining (NHEJ) for the efficient repair of chromosomal DNA double-strand breaks. A key feature of biological sources of strand breaks is associated nucleotide damage, including base loss (abasic or apurinic/apyrimidinic (AP) sites). At single-strand breaks, 5'-terminal abasic sites are excised by the 5'-deoxyribose-5-phosphate (5'-dRP) lyase activity of DNA polymerase beta (pol beta): here we show, in vitro and in cells, that accurate and efficient repair by NHEJ of double-strand breaks with such damage similarly requires 5'-dRP/AP lyase activity. Classically defined NHEJ is moreover uniquely effective at coupling this end-cleaning step to joining in cells, helping to distinguish this pathway from otherwise robust alternative NHEJ pathways. The NHEJ factor Ku can be identified as an effective 5'-dRP/AP lyase. In a similar manner to other lyases, Ku nicks DNA 3' of an abasic site by a mechanism involving a Schiff-base covalent intermediate with the abasic site. We show by using cell extracts that Ku is essential for the efficient removal of AP sites near double-strand breaks and, consistent with this result, that joining of such breaks is specifically decreased in cells complemented with a lyase-attenuated Ku mutant. Ku had previously been presumed only to recognize ends and recruit other factors that process ends; our data support an unexpected direct role for Ku in end-processing steps as well.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2859099/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉 〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2859099/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Roberts, Steven A -- Strande, Natasha -- Burkhalter, Martin D -- Strom, Christina -- Havener, Jody M -- Hasty, Paul -- Ramsden, Dale A -- CA 84442/CA/NCI NIH HHS/ -- P01 AG17242/AG/NIA NIH HHS/ -- R01 CA084442/CA/NCI NIH HHS/ -- R01 CA084442-10/CA/NCI NIH HHS/ -- R01 CA76317-05A1/CA/NCI NIH HHS/ -- England -- Nature. 2010 Apr 22;464(7292):1214-7. doi: 10.1038/nature08926. Epub 2010 Apr 11.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Biophysics, Lineberger Comprehensive Cancer Center, and Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20383123" target="_blank"〉PubMed〈/a〉
Keywords:
Animals
;
Antigens, Nuclear/genetics/*metabolism
;
*Biocatalysis
;
Cell Extracts
;
Cell Line
;
*DNA Breaks, Double-Stranded
;
*DNA Damage
;
*DNA Repair
;
DNA-(Apurinic or Apyrimidinic Site) Lyase/genetics/*metabolism
;
DNA-Binding Proteins/genetics/*metabolism
;
Fibroblasts
;
HeLa Cells
;
Humans
;
Mice
;
Ribosemonophosphates/*metabolism
;
Schiff Bases/chemistry
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
,
Natural Sciences in General
,
Physics
