We recently described a yeast assay suitable for genetic screening in which simple religation nonhomologous end-joining (NHEJ) and single-strand annealing (SSA) compete for repair of an I-SceI-created double-strand break. Here, the required allele has been introduced into an array of 4781 MATa deletion mutants and each strain screened individually. Two mutants (rad52 and srs2) showed a clear in...

Canonical non-homologous end joining (c-NHEJ) repairs DNA double-strand breaks (DSBs) in G1 cells with biphasic kinetics. We show that DSBs repaired with slow kinetics, including those localizing to heterochromatic regions or harboring additional lesions at the DSB site, undergo resection prior to repair by c-NHEJ and not alt-NHEJ. Resection-dependent c-NHEJ represents an inducible process duri...

Double-strand breaks (DSBs) are one of the most harmful DNA lesions. Cells utilize two main pathways for DSB repair: homologous recombination (HR) and nonhomologous end-joining (NHEJ). NHEJ can be subdivided into the KU-dependent classical NHEJ (c-NHEJ) and the more error-prone KU-independent backup-NHEJ (b-NHEJ) pathways, involving the poly (ADP-ribose) polymerases (PARPs). However, in the abs...

In mammalian cells, ionizing radiation (IR)-induced DNA double-strand breaks (DSBs) are repaired in all phases of the cell cycle predominantly by classical, DNA-PK-dependent nonhomologous end joining (D-NHEJ). Homologous recombination repair (HRR) is functional during the S- and G2-phases, when a sister chromatid becomes available. An error-prone, alternative form of end joining, operating as b...

In mammalian cells, the main pathway for DNA double-strand breaks (DSBs) repair is classical non-homologous end joining (C-NHEJ). An alternative or back-up NHEJ (B-NHEJ) pathway has emerged which operates preferentially under C-NHEJ defective conditions. Although B-NHEJ appears particularly relevant to genomic instability associated with cancer, its components and regulation are still largely u...

Cells of higher eukaryotes process double strand breaks (DSBs) in their genome using a non-homologous end joining apparatus that utilizes DNA-PK and other well characterized factors (D-NHEJ). Cells with defects in D-NHEJ, repair the majority of DSBs using a slow-repair pathway which is independent of genes of the RAD52 epistasis group and functions as a backup (B-NHEJ). Recent studies implicate...

Non-homologous end joining (NHEJ) is the preferred pathway for repair of DNA double-strand breaks in humans. Here we describe three structural aspects pathway: stages, scaffolds and strings. We discuss orchestration to guarantee robust efficient NHEJ. focus on studies over past two decades, not only using X-ray diffraction, but also increasingly exploiting cryo-EM investigate macromolecular ass...

Inneuroblastoma,MYCNgenomicamplificationand segmental chromosomal alterations including1por11q lossofheterozygocity and/or 17q gain are associated with progression and poor clinical outcome. Segmental alterations are the strongest predictor of relapse and result from unbalanced translocations attributable to erroneous repair of chromosomal breaks. Although sequence analysis of affected genomic ...

Background: PALF binds to the NHEJ protein, XRCC4. Results: PALF is a single-stranded DNA endonuclease and 3’ exonuclease. PALF can coordinate with known NHEJ proteins to achieve ligation. Conclusion: In vitro and in vivo, PALF is able to cooperate with NHEJ proteins to join double-stranded DNA breaks. Significance: A second nuclease, in addition to Artemis, can function with NHEJ proteins to a...

BACKGROUND Non-homologous end joining (NHEJ) is the main repair pathway for DNA double strand breaks (DSBs) induced by ionizing radiation in mammalian cells. Subsets of cancer patients are hypersensitive to radiotherapy after standard doses. We sought to determine the radiosensitivity of human lymphoblastic cells (LB0005) for the abnormality in NHEJ components. METHODS Lymphoblastic (LB0005) ...