Role of the oxidized form of XRCC1 in protection against extreme oxidative stress.
The multi-domain protein XRCC1 is without catalytic activity, but can interact with a number of known repair proteins. The interaction between the N-terminal domain (NTD) of XRCC1 and DNA polymerase β (pol β) is critical for recruitment of pol β to sites of DNA damage and repair. Crystallographic and NMR approaches have identified oxidized and reduced forms of the XRCC1 NTD, and the corresponding forms of XRCC1 have been identified in cultured mouse fibroblast cells. Both forms of NTD interact with pol β, but the interaction is much stronger with the oxidized form. The potential for formation of the C12-C20 oxidized conformation can be removed by alanine substitution at C12 (C12A) leading to stabilized reduced XRCC1 with a lower pol β binding affinity. Here, we compare cells expressing C12A XRCC1 (XRE8) with those expressing wild-type XRCC1 (XC5). Reduced C12A XRCC1 is detected at sites of micro-irradiation DNA damage, but provides slower recruitment of pol β. Expression of reduced XRCC1 does not affect sensitivity to MMS or H2O2.In contrast, further oxidative stress imposed by glutathione depletion results in increased sensitization of reduced XRCC1-expressing cells to H2O2compared with wild-type XRCC1-expressing cells. There is no indication of enhanced H2O2-generated free radicals or DNA strand breaks in XRE8 cells. However, elevated cellular PAR is found following H2O2exposure, suggesting BER deficiency of H2O2-induced damage in the C12A expressing cells.
Genomic Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, Research Triangle Park, NC 27709, USA.
Julie K
JK
Horton
Genomic Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, Research Triangle Park, NC 27709, USA.
Hannah J
HJ
Seddon
Genomic Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, Research Triangle Park, NC 27709, USA.
Ming-Lang
ML
Zhao
Genomic Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, Research Triangle Park, NC 27709, USA.
Natalie R
NR
Gassman
Signal Transduction Laboratory, NIEHS, National Institutes of Health, Research Triangle Park, NC 27709, USA.
Agnes K
AK
Janoshazi
Genomic Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, Research Triangle Park, NC 27709, USA.
Donna F
DF
Stefanick
Genomic Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, Research Triangle Park, NC 27709, USA. Electronic address: wilson5@niehs.nih.gov.
Samuel H
SH
Wilson
D000818:Animals; D002478:Cells, Cultured; D004249:DNA Damage; D019951:DNA Polymerase beta / Q000378:metabolism; D004260:DNA Repair; D005347:Fibroblasts / Q000502:physiology*; D006861:Hydrogen Peroxide / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D016297:Mutagenesis, Site-Directed; D009154:Mutation / Q000235:genetics; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D011485:Protein Binding; D011487:Protein Conformation; D055550:Protein Stability; D016159:Tumor Suppressor Protein p53 / Q000235:genetics; D000076105:X-ray Repair Cross Complementing Protein 1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D016159:Tumor Suppressor Protein p53; D000076105:X-ray Repair Cross Complementing Protein 1; D006861:Hydrogen Peroxide; D019951:DNA Polymerase beta
DNA polymerase β; Glutathione depletion; Hydrogen peroxide; Methyl methanesulfonate; PAR; XRCC1