XLF acts as a flexible connector during non-homologous end joining

Carney, Sean M.; Moreno, Andrew; Piatt, Sadie; Cisneros‐Aguirre, Metztli; Lopezcolorado, Felicia Wednesday; Stark, Jeremy M.; Loparo, Joseph J.

doi:10.1101/2020.07.29.227033

Cited by 7 publications

(8 citation statements)

References 45 publications

(127 reference statements)

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“…With this density map, we directly docked in the subunit models from the LR complex as rigid bodies, revealing a very similar overall architecture to the LR complex, except for the two DNA-PKcs molecules. In accord with smFRET studies using Xenopus egg extracts 27,28 , Ku and LigIV-XRCC4 subcomplexes reside on opposite sides of the complex, with one XLF dimer bridging the two halves (Fig. 3b, Supplementary Video 2).…”

Section: Architecture Of the Sr Synaptic Complexsupporting

confidence: 69%

Structural basis of long-range to short-range synaptic transition in NHEJ

Chen

Lee

Naila

et al. 2021

Nature

113

138

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DNA double-strand breaks (DSBs) are the most cytotoxic form of DNA damage, with their aberrant repair linked with carcinogenesis 1,2 . The conserved error-prone Non-Homologous End-Joining (NHEJ) pathway plays a key role in determining the effects of DSB-inducing agents used to treat cancer as well as the generation of antibody and T cell receptor diversity 2,3 . Here, we applied single-particle cryo-electron microscopy (EM) to visualize two key DNA-protein complexes formed by NHEJ factors. Ku, DNA-PKcs, LigIV-XRCC4, and XLF form a Long-range synaptic complex, in which the DNA ends are held ~115 Å apart. Two DNA end-bound Ku-DNA-PKcs subcomplexes are linked by DNA-PKcs-DNA-PKcs interactions and a LigIV-XRCC4-XLF-XRCC4-LigIV scaffold. The relative orientation of the DNA-PKcs molecules suggests a mechanism for auto-phosphorylation in trans, leading to dissociation of DNA-PKcs and transition into the Short-range synaptic complex. Within this complex, the Ku-bound DNA ends are aligned for processing and ligation by the XLF-anchored scaffold, and a single LigIV catalytic domain is stably associated with a nick between the two Ku molecules, suggesting that joining of both strands of a DSB involves both LigIV molecules.

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Section: Architecture Of the Sr Synaptic Complexsupporting

confidence: 69%

Structural basis of long-range to short-range synaptic transition in NHEJ

Chen

Lee

Naila

et al. 2021

Nature

113

138

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“…From our cryo-EM data we were able to reveal a dimeric form of DNA-PK mediated by a central XLF homodimer. Recently, single-molecule fluorescence imaging in Xenopus laevis egg extract demonstrates that a single XLF homodimer facilitates assembly of a synaptic complex in NHEJ (Carney et al, 2020;Graham et al, 2018). We observe the central role of XLF in our dimeric form of DNA-PK that would ultimately allow correct positioning of DNA ends prior to ligation.…”

Section: Discussionmentioning

confidence: 72%

Cryo-EM of NHEJ supercomplexes provides insights into DNA repair

et al. 2021

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“…Next, a larger complex is formed by DNA-PK, XLF, LIG4 and XRCC4 [ 47 ]. More recently, the XLF was proposed to be a flexible connector in this model, by interacting with both Ku70/Ku80 and XRCC4/LIG4/DSB [ 48 ].…”

Section: Discussionmentioning

confidence: 99%

Non-Homologous End Joining Factors XLF, PAXX and DNA-PKcs Maintain the Neural Stem and Progenitor Cell Population

Gago-Fuentes

Oksenych

2020

Biomolecules

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Non-homologous end-joining (NHEJ) is a major DNA repair pathway in mammalian cells that recognizes, processes and fixes DNA damage throughout the cell cycle and is specifically important for homeostasis of post-mitotic neurons and developing lymphocytes. Neuronal apoptosis increases in the mice lacking NHEJ factors Ku70 and Ku80. Inactivation of other NHEJ genes, either Xrcc4 or Lig4, leads to massive neuronal apoptosis in the central nervous system (CNS) that correlates with embryonic lethality in mice. Inactivation of either Paxx, Mri or Dna-pkcs NHEJ gene results in normal CNS development due to compensatory effects of Xlf. Combined inactivation of Xlf/Paxx, Xlf/Mri and Xlf/Dna-pkcs, however, results in late embryonic lethality and high levels of apoptosis in CNS. To determine the impact of NHEJ factors on the early stages of neurodevelopment, we isolated neural stem and progenitor cells from mouse embryos and investigated proliferation, self-renewal and differentiation capacity of these cells lacking either Xlf, Paxx, Dna-pkcs, Xlf/Paxx or Xlf/Dna-pkcs. We found that XRCC4-like factor (XLF), DNA-dependent protein kinase catalytic subunit (DNA-PKcs) and paralogue of XRCC4 and XLF (PAXX) maintain the neural stem and progenitor cell populations and neurodevelopment in mammals, which is particularly evident in the double knockout models.

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XLF acts as a flexible connector during non-homologous end joining

Cited by 7 publications

References 45 publications

Structural basis of long-range to short-range synaptic transition in NHEJ

Structural basis of long-range to short-range synaptic transition in NHEJ

Cryo-EM of NHEJ supercomplexes provides insights into DNA repair

Non-Homologous End Joining Factors XLF, PAXX and DNA-PKcs Maintain the Neural Stem and Progenitor Cell Population

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