| 31. |
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| 32. |
- Parsons, Jason L., et al.
(författare)
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XRCC1 phosphorylation by CK2 is required for its stability and efficient DNA repair
- 2010
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Ingår i: DNA Repair. - : Elsevier BV. - 1568-7864 .- 1568-7856. ; 9:7, s. 835-841
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Tidskriftsartikel (refereegranskat)abstract
- XRCC1 is a scaffold protein that interacts with several DNA repair proteins and plays a critical role in DNA base excision repair (BER). XRCC1 protein is in a tight complex with DNA ligase III alpha (Lig III) and this complex is involved in the ligation step of both BER and repair of DNA single strand breaks. The majority of XRCC1 has previously been demonstrated to exist in a phosphorylated form and cells containing mutant XRCC1, that is unable to be phosphorylated, display a reduced rate of single strand break repair. Here, in an unbiased assay, we demonstrate that the cytoplasmic form of the casein kinase 2 (CK2) protein is the major protein kinase activity involved in phosphorylation of XRCC1 in human cell extracts and that XRCC1 phosphorylation is required for XRCC1-Lig III complex stability. We demonstrate that XRCC1-Lig III complex containing mutant XRCC1, in which CK2 phosphorylation sites have been mutated, is unstable. We also find that a knockdown of CK2 by siRNA results in both reduced XRCC1 phosphorylation and stability, which also leads to a reduced amount of Lig III and accumulation of DNA strand breaks. We therefore propose that CK2 plays an important role in DNA repair by contributing to the stability of XRCC1-Lig III complex.
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| 33. |
- Persson, Örjan, 1974, et al.
(författare)
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UspB, a member of the sigma-S regulon, facilitates RuvC resolvase function.
- 2010
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Ingår i: DNA repair. - : Elsevier BV. - 1568-7856 .- 1568-7864. ; 9:11, s. 1162-9
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Tidskriftsartikel (refereegranskat)abstract
- A growing body of evidence shows that there is an intimate connection between proteins required for genome stability and stationary phase survival. In this work we show that the integral membrane protein UspB, a member of the RpoS regulon, is required for proper DNA repair as mutants lacking uspB are hypersensitive to several DNA damaging agents including ultraviolet light, mitomycin C, bleomycin and ciprofloxacin. Genetic and physical studies demonstrate that UspB acts in the RuvABC recombination repair pathway and removing uspB creates a phenocopy of the Holliday junction resolvase mutant, ruvC. Further, we show that the uspB mutant phenotype can be suppressed by ectopic overproduction of RuvC and that both ruvC and uspB mutants can be suppressed by inactivating recD. The fact that RuvABC-dependent repair requires UspB for proper activity suggests that the sigma-S regulon works together with DNA repair pathways under stress conditions to defend the cell against genotoxic stress.
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| 34. |
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| 35. |
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| 36. |
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| 37. |
- Singh, Umashankar, et al.
(författare)
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Evidence for multiple forms and modifications of human POT1
- 2013
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Ingår i: DNA Repair. - : Elsevier BV. - 1568-7864 .- 1568-7856. ; 12:11, s. 876-877
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Tidskriftsartikel (refereegranskat)abstract
- Human POT1, a widely studied telomere protector protein is perceived to be expressed as a single 70 kDa form. A survey of the literature as well as different commercially available antibodies against POT1 suggests occurrence of multiple forms of POT1. Knowledge about possible various forms of an important protein like POT1 is necessary for our understanding about its function. We have discovered that POT1 exists in at least three consistently occurring forms; 90,70 and 45 kDa. The unexpected molecular weights of POT1 seem to be associated with SUMO1 and ubiquitin conjugation; the latter occurring at a double lysine residue at 289-KK-290. We also present evidence that the relative abundance of the different POT1 forms can be altered by experimental modulation of POT1 nuclear localization. We thus present strong evidence that there are post-translational modifications of POT1 that can affect its molecular weight as well as intracellular localization and function.
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| 38. |
- Singh, Vandana, 1985, et al.
(författare)
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Shining light on single-strand lesions caused by the chemotherapy drug bleomycin
- 2021
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Ingår i: DNA Repair. - : Elsevier BV. - 1568-7864 .- 1568-7856. ; 105
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Tidskriftsartikel (refereegranskat)abstract
- Quantification of the DNA damage induced by chemotherapy in patient cells may aid in personalization of the dose used. However, assays to evaluate individual patient response to chemotherapy are not available today. Here, we present an assay that quantifies single-stranded lesions caused by the chemotherapeutic drug Bleomycin (BLM) in peripheral blood mononuclear cells (PBMCs) isolated from healthy individuals. We use base excision repair (BER) enzymes to process the DNA damage induced by BLM and then extend the processed sites with fluorescent nucleotides using a DNA polymerase. The fluorescent patches are quantified on single DNA molecules using fluorescence microscopy. Using the assay, we observe a significant variation in the in vitro induced BLM damage and its repair for different individuals. Treatment of the cells with the BER inhibitor CRT0044876 leads to a lower level of repair of BLM-induced damage, indicating the ability of the assay to detect a compromised DNA repair in patients. Overall, the data suggest that our assay could be used to sensitively detect the variation in BLM-induced DNA damage and repair in patients and can potentially be able to aid in personalizing patient doses.
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| 39. |
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| 40. |
- Stone, Jana E, et al.
(författare)
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Lesion bypass by S. cerevisiae Pol ζ alone
- 2011
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Ingår i: DNA Repair. - : Elsevier. - 1568-7864 .- 1568-7856. ; 10:8, s. 826-834
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Tidskriftsartikel (refereegranskat)abstract
- DNA polymerase zeta (Pol ζ) participates in translesion synthesis (TLS) of DNA adducts that stall replication fork progression. Previous studies have led to the suggestion that the primary role of Pol ζ in TLS is to extend primers created when another DNA polymerase inserts nucleotides opposite lesions. Here we test the non-exclusive possibility that Pol ζ can sometimes perform TLS in the absence of any other polymerase. To do so, we quantified the efficiency with which S. cerevisiae Pol ζ bypasses abasic sites, cis-syn cyclobutane pyrimidine dimers and (6-4) photoproducts. In reactions containing dNTP concentrations that mimic those induced by DNA damage, a Pol ζ derivative with phenylalanine substituted for leucine 979 at the polymerase active site bypasses all three lesions at efficiencies between 27 and 73%. Wild-type Pol ζ also bypasses these lesions, with efficiencies that are lower and depend on the sequence context in which the lesion resides. The results are consistent with the hypothesis that, in addition to extending aberrant termini created by other DNA polymerases, Pol ζ has the potential to be the sole DNA polymerase involved in TLS.
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