DNA recombination

  • Article
    | Open Access

    Structural studies of the CRISPR-associated transposon comprising Cas12k, TnsC, TnsB and TniQ from Scytonema hofmannii using cryo-electron microscopy reveal insights into the architecture and mechanism of RNA-guided DNA transposition.

    • Jung-Un Park
    • , Amy Wei-Lun Tsai
    •  & Elizabeth H. Kellogg
  • Article
    | Open Access

    Observations of rapid repair of double-stranded DNA breaks in sister choromosomes in Escherichia coli are consistent with a reduced-dimensionality-search model of RecA-mediated repair.

    • Jakub Wiktor
    • , Arvid H. Gynnå
    •  & Johan Elf
  • Article |

    A small proportion of Spo11-dependent DNA double-strand breaks are ‘double cuts’—adjacent breaks that occur in concert—revealing that gap repair during meiosis includes that of DNA gaps generated by Spo11 itself.

    • Dominic Johnson
    • , Margaret Crawford
    •  & Matthew J. Neale
  • Article |

    Long-distance V(D)J recombination is facilitated by contraction of the Igh locus and linear RAG scanning along chromatin, both driven by cohesin-mediated loop extrusion, which allows recombination of widely separated gene segments to occur.

    • Hai-Qiang Dai
    • , Hongli Hu
    •  & Frederick W. Alt
  • Article |

    Cryo-electron microscopy structures of the bacterial recombination protein RecA with DNA, and of RecA–D-loop complexes, provide insights into the double-stranded DNA opening, homology search and strand-exchange processes of homologous recombination.

    • Haijuan Yang
    • , Chun Zhou
    •  & Nikola P. Pavletich
  • Article |

    In Escherichia coli, the control of RNA polymerase backtracking by transcription elongation factors impairs DNA break repair by affecting RecBCD resection and consequently RecA loading at sites far removed from the original DNA break.

    • Priya Sivaramakrishnan
    • , Leonardo A. Sepúlveda
    •  & Christophe Herman
  • Letter |

    DNA repair by break-induced replication begins with the Rad51-mediated invasion of single-stranded DNA into a double-stranded donor template; this study shows that successful recombination between highly mismatched substrates can occur when only five consecutive bases can be paired and that mismatch correction is most efficient near the invading end of the recipient strand.

    • Ranjith Anand
    • , Annette Beach
    •  & James Haber
  • Letter |

    Retroviruses such as HIV rely on the intasome, a tetramer of integrase protein bound to the viral DNA ends interacting with host chromatin, for integration into the host genome; the structure of the intasome as it interacts with a nucleosome is now solved, giving insight into the integration process.

    • Daniel P. Maskell
    • , Ludovic Renault
    •  & Peter Cherepanov
  • Letter |

    Loss of REV7 is shown to regulate end resection of double-stranded DNA breaks in BRCA1-deficient cells, leading to PARP inhibitor resistance and restoration of homologous recombination; REV7 dictates pathway choice in BRCA1-deficient cells and during immunoglobulin class switching.

    • Guotai Xu
    • , J. Ross Chapman
    •  & Sven Rottenberg
  • Letter |

    Meiotic recombination is initiated by a fairly uniform distribution of hundreds of DNA double-strand breaks catalysed by the Spo11 protein; here, Tel1 (orthologue of human ATM) is shown to be required for the localized inhibition that prevents double-strand breaks from forming close to one another.

    • Valerie Garcia
    • , Stephen Gray
    •  & Matthew J. Neale
  • Letter |

    The MRX complex, required for double-strand break (DSB) repair by homologous recombination, has 3′ to 5′ exonuclease activity, but homologous recombination at a DSB uses a 3′-tailed molecule, which requires resection of the 5′ strand; here it is shown that in yeast, Sae2 nuclease promotes MRX to make an initial endonucleolytic cut on the 5′ strand that may allow MRX to digest the 5′ strand back to the end in a 3′ to 5′ fashion.

    • Elda Cannavo
    •  & Petr Cejka
  • Letter |

    Endogenous RNA transcripts are shown to mediate recombination with yeast chromosomal DNA; as the level of RNAs in the nucleus is quite high, these results may open up new understanding of the plasticity of repair and genome instability mechanisms.

    • Havva Keskin
    • , Ying Shen
    •  & Francesca Storici
  • Letter |

    A dual-function helicase–nuclease, typified by RecBCD in Escherichia coli, acts on free DNA ends during bacterial double-stranded break repair until it reaches a χ sequence at which it pauses before continuing with modified enzymatic properties; here several crystal structures of the related AddAB enzyme from Bacillus subtilis bound to χ-containing DNA are presented, offering insight into χ recognition and its effect on DNA translocation.

    • Wojciech W. Krajewski
    • , Xin Fu
    •  & Dale B. Wigley
  • Letter |

    Meiotic crossover regulation is proposed to operate as a self-limiting system in which meiotic chromosome structures create an environment that promotes crossovers, which in turn modify chromosome structures to inhibit crossover formation at additional neighbouring sites.

    • Diana E. Libuda
    • , Satoru Uzawa
    •  & Anne M. Villeneuve
  • Letter |

    Interstrand crosslink (ICL) repair involves proteins whose mutation results in the disorder Fanconi anaemia: here gene knockdown studies in mice show that the absence of HELQ, a protein previously implicated in ICL repair, compromises germ cell development and results in tumour predisposition due to defective recombination at damaged replication forks.

    • Carrie A. Adelman
    • , Rafal L. Lolo
    •  & Simon J. Boulton
  • Article |

    In vitro and in vivo, the yeast Pif1 helicase is able to unwind four-stranded G-quadruplex (G4) DNA efficiently and suppress the genomic instability that occurs at such structures; these G4 maintenance activities are conserved among evolutionarily diverse Pif1 family helicases, including human PIF1, demonstrating the importance of this activity throughout evolution.

    • Katrin Paeschke
    • , Matthew L. Bochman
    •  & Virginia A. Zakian
  • Letter |

    A new mechanism of chromosomal rearrangement is identified through the observation that broken or collapsed DNA replication forks restarted by homologous recombination have a high propensity for U-turns at short inverted repeats; the error-prone nature of this mechanism is suggested to contribute to gross chromosomal rearrangements and copy-number variations present in cancer and other genomic disorders.

    • Ken’Ichi Mizuno
    • , Izumi Miyabe
    •  & Johanne M. Murray
  • Letter |

    The E1 and E2 glycoproteins of alphaviruses form heterodimers and assemble into spikes on the virus surface, which mediate receptor binding and endocytosis. When the virion encounters acidic pH in the endosome E1 and E2 dissociate and E1 triggers fusion with the endosomal membrane. Two papers now provide the first crystal structures for glycoprotein complexes incorporating E2 at acidic and neutral pH, respectively. Together they provide insight into how fusion activation is controlled in alphaviruses.

    • James E. Voss
    • , Marie-Christine Vaney
    •  & Félix A. Rey
  • Letter |

    Here, human genome-wide single-nucleotide polymorphism (SNP) data from more than 15,000 parent–offspring pairs have been used to construct the first recombination maps that are based on directly observed recombination events. The data reveal interesting differences between the sexes: for instance, in males recombination tends to shuffle exons, whereas in females it generates new combinations of nearby genes. Comparison of these maps with others also reveals population differences.

    • Augustine Kong
    • , Gudmar Thorleifsson
    •  & Kari Stefansson
  • Letter |

    To facilitate their proper segregation, duplicated meiotic chromosomes are physically joined by crossovers. Crossover formation begins with the introduction of meiosis-specific double-strand breaks. These authors identify a new gene in Caenorhabditis elegans, xnd-1, that is required for crossover distribution on both the X and the autosomal chromosomes. Preliminary data suggest that xnd-1 does this by regulating acetylation of histone H2A on lysine 5.

    • Cynthia R. Wagner
    • , Lynnette Kuervers
    •  & Judith L. Yanowitz