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XB-ART-54850
DNA Repair (Amst) December 9, 2006; 5 (12): 1439-48.
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NEIL2-initiated, APE-independent repair of oxidized bases in DNA: Evidence for a repair complex in human cells.

Das A , Wiederhold L , Leppard JB , Kedar P , Prasad R , Wang H , Boldogh I , Karimi-Busheri F , Weinfeld M , Tomkinson AE , Wilson SH , Mitra S , Hazra TK .


Abstract
DNA glycosylases/AP lyases initiate repair of oxidized bases in the genomes of all organisms by excising these lesions and then cleaving the DNA strand at the resulting abasic (AP) sites and generate 3'' phospho alpha,beta-unsaturated aldehyde (3'' PUA) or 3'' phosphate (3'' P) terminus. In Escherichia coli, the AP-endonucleases (APEs) hydrolyze both 3'' blocking groups (3'' PUA and 3'' P) to generate the 3''-OH termini needed for repair synthesis. In mammalian cells, the previously characterized DNA glycosylases, NTH1 and OGG1, produce 3'' PUA, which is removed by the only AP-endonuclease, APE1. However, APE1 is barely active in removing 3'' phosphate generated by the recently discovered mammalian DNA glycosylases NEIL1 and NEIL2. We showed earlier that the 3'' phosphate generated by NEIL1 is efficiently removed by polynucleotide kinase (PNK) and not APE1. Here we show that the NEIL2-initiated repair of 5-hydroxyuracil (5-OHU) similarly requires PNK. We have also observed stable interaction between NEIL2 and other BER proteins DNA polymerase beta (Pol beta), DNA ligase IIIalpha (Lig IIIalpha) and XRCC1. In spite of their limited sequence homology, NEIL1 and NEIL2 interact with the same domains of Pol beta and Lig IIIalpha. Surprisingly, while the catalytically dispensable C-terminal region of NEIL1 is the common interacting domain, the essential N-terminal segment of NEIL2 is involved in analogous interaction. The BER proteins including NEIL2, PNK, Pol beta, Lig IIIalpha and XRCC1 (but not APE1) could be isolated as a complex from human cells, competent for repair of 5-OHU in plasmid DNA.

PubMed ID: 16982218
PMC ID: PMC2805168
Article link: DNA Repair (Amst)
Grant support: [+]

Species referenced: Xenopus
Genes referenced: neil1 neil2 ogg1 ube2k xrcc1

References [+] :
Ames, Oxidants, antioxidants, and the degenerative diseases of aging. 1993, Pubmed