| 1. |
- Luijsterburg, MS, et al.
(författare)
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Stochastic and reversible assembly of a multiprotein DNA repair complex ensures accurate target site recognition and efficient repair
- 2010
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Ingår i: The Journal of cell biology. - : Rockefeller University Press. - 1540-8140 .- 0021-9525. ; 189:3, s. 445-463
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Tidskriftsartikel (refereegranskat)abstract
- To understand how multiprotein complexes assemble and function on chromatin, we combined quantitative analysis of the mammalian nucleotide excision DNA repair (NER) machinery in living cells with computational modeling. We found that individual NER components exchange within tens of seconds between the bound state in repair complexes and the diffusive state in the nucleoplasm, whereas their net accumulation at repair sites evolves over several hours. Based on these in vivo data, we developed a predictive kinetic model for the assembly and function of repair complexes. DNA repair is orchestrated by the interplay of reversible protein-binding events and progressive enzymatic modifications of the chromatin substrate. We demonstrate that faithful recognition of DNA lesions is time consuming, whereas subsequently, repair complexes form rapidly through random and reversible assembly of NER proteins. Our kinetic analysis of the NER system reveals a fundamental conflict between specificity and efficiency of chromatin-associated protein machineries and shows how a trade off is negotiated through reversibility of protein binding.
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| 2. |
- Marteijn, JA, et al.
(författare)
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Nucleotide excision repair-induced H2A ubiquitination is dependent on MDC1 and RNF8 and reveals a universal DNA damage response
- 2009
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Ingår i: The Journal of cell biology. - : Rockefeller University Press. - 1540-8140 .- 0021-9525. ; 186:6, s. 835-847
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Tidskriftsartikel (refereegranskat)abstract
- Chromatin modifications are an important component of the of DNA damage response (DDR) network that safeguard genomic integrity. Recently, we demonstrated nucleotide excision repair (NER)–dependent histone H2A ubiquitination at sites of ultraviolet (UV)-induced DNA damage. In this study, we show a sustained H2A ubiquitination at damaged DNA, which requires dynamic ubiquitination by Ubc13 and RNF8. Depletion of these enzymes causes UV hypersensitivity without affecting NER, which is indicative of a function for Ubc13 and RNF8 in the downstream UV–DDR. RNF8 is targeted to damaged DNA through an interaction with the double-strand break (DSB)–DDR scaffold protein MDC1, establishing a novel function for MDC1. RNF8 is recruited to sites of UV damage in a cell cycle–independent fashion that requires NER-generated, single-stranded repair intermediates and ataxia telangiectasia–mutated and Rad3-related protein. Our results reveal a conserved pathway of DNA damage–induced H2A ubiquitination for both DSBs and UV lesions, including the recruitment of 53BP1 and Brca1. Although both lesions are processed by independent repair pathways and trigger signaling responses by distinct kinases, they eventually generate the same epigenetic mark, possibly functioning in DNA damage signal amplification.
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