DNA polymerase μ is a global player in the repair of non-homologous end-joining substrates

Chayot, Romain; Montagne, Benjamin; Ricchetti, Miria

doi:10.1016/j.dnarep.2011.09.016

Cited by 15 publications

(8 citation statements)

References 38 publications

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“…For example, resistance to ionizing radiation, a hallmark of proficiency in NHEJ, is not affected by deficiency in Pol λ (16,17), whereas the effects of deficiency in Pol μ on resistance to ionizing radiation depends partly on cell type (16,18,19). Effects of these polymerases on the fidelity of NHEJ have also been observed (9,10,16,(20)(21)(22)(23), although interpretations vary as to whether differences in catalytic activities are important (i.e., they are redundant), or even if their catalytic activities are relevant at all. Much of the uncertainty can be attributed to changes in relative expression level comparing different cell types and especially to difficulties in unambiguously defining the substrates on which the polymerases acted in these cellular experiments.…”

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confidence: 82%

Essential role for polymerase specialization in cellular nonhomologous end joining

Pryor

Waters

Aza

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Nonhomologous end joining (NHEJ) repairs chromosome breaks and must remain effective in the face of extensive diversity in broken end structures. We show here that this flexibility is often reliant on the ability to direct DNA synthesis across strand breaks, and that polymerase (Pol) μ and Pol λ are the only mammalian DNA polymerases that have this activity. By systematically varying substrate in cells, we show each polymerase is uniquely proficient in different contexts. The templating nucleotide is also selected differently, with Pol μ using the unpaired base adjacent to the downstream 5′ phosphate even when there are available template sites further upstream of this position; this makes Pol μ more flexible but also less accurate than Pol λ. Loss of either polymerase alone consequently has clear and distinguishable effects on the fidelity of repair, but end remodeling by cellular nucleases and the remaining polymerase helps mitigate the effects on overall repair efficiency. Accordingly, when cells are deficient in both polymerases there is synergistic impact on NHEJ efficiency, both in terms of repair of defined substrates and cellular resistance to ionizing radiation. Pol μ and Pol λ thus provide distinct solutions to a problem for DNA synthesis that is unique to this pathway and play a key role in conferring on NHEJ the flexibility required for accurate and efficient repair.nonhomologous end joining | double-strand break repair | Pol X | polymerase mu | polymerase lambda

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confidence: 82%

Essential role for polymerase specialization in cellular nonhomologous end joining

Pryor

Waters

Aza

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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“…Accordingly, pol μ is essential for mitigating deletion during NHEJ of IgL recombination intermediates [98]. Analysis of NHEJ in pol μ-deficient mice [99] and cultured fibroblasts [100] also confirms an important role for pol μ in promoting NHEJ in non-lymphoid cell types, though it has been suggested this role is independent of pol μ’s synthesis activity [100]. Pol λ appears to have a mild impact on NHEJ, especially in non-lymphoid cell types [95], possibly because its repertoire of substrates may be a subset of Pol μ’s [82].…”

Section: Nhej Is a Multi-protein Machinementioning

confidence: 99%

Nonhomologous end joining: A good solution for bad ends

et al. 2014

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“…While Pol beta is mainly involved in single‐stranded break (SSB) DNA repair, the others are involved in DSB repair. Pol lambda (Bebenek et al , ) and Pol mu directly intervene in NHEJ (Aoufouchi et al , ; Domínguez et al , ; Chayot et al , , ), and Pol mu has been shown to have a gradient of different activities (Nick McElhinny et al , ) with more or less tolerance/efficiency with respect to the various substrates it encounters at a DNA synapsis. Tdt, which shares 42% sequence identity with Pol mu, is located at the extreme end of the spectrum of possible Pol mu activities, because it is completely template independent.…”

Section: Introductionmentioning

confidence: 99%

Structural basis for a novel mechanism of DNA bridging and alignment in eukaryotic DSB DNA repair

et al. 2015

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Eukaryotic DNA polymerase mu of the PolX family can promote the association of the two 3 0 -protruding ends of a DNA double-strand break (DSB) being repaired (DNA synapsis) even in the absence of the core non-homologous end-joining (NHEJ) machinery. Here, we show that terminal deoxynucleotidyltransferase (TdT), a closely related PolX involved in V(D)J recombination, has the same property. We solved its crystal structure with an annealed DNA synapsis containing one micro-homology (MH) base pair and one nascent base pair. This structure reveals how the N-terminal domain and Loop 1 of Tdt cooperate for bridging the two DNA ends, providing a templating base in trans and limiting the MH search region to only two base pairs. A network of ordered water molecules is proposed to assist the incorporation of any nucleotide independently of the in trans templating base. These data are consistent with a recent model that explains the statistics of sequences synthesized in vivo by Tdt based solely on this dinucleotide step. Site-directed mutagenesis and functional tests suggest that this structural model is also valid for Pol mu during NHEJ.

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DNA polymerase μ is a global player in the repair of non-homologous end-joining substrates

Cited by 15 publications

References 38 publications

Essential role for polymerase specialization in cellular nonhomologous end joining

Essential role for polymerase specialization in cellular nonhomologous end joining

Nonhomologous end joining: A good solution for bad ends

Structural basis for a novel mechanism of DNA bridging and alignment in eukaryotic DSB DNA repair

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