• Article
    | Open Access

    In Saccharomyces cerevisiae, unchecked proliferation of Ty1 retrotransposons is controlled by the process of copy number control (CNC), which requires the p22/p18 protein, translated from an internal transcript within the Ty1 GAG gene. Here, the authors present the 2.8 Å crystal structure of a minimal p18 from Ty1-Gag that is able to restrict Ty1 transposition and identify two dimer interfaces in p18, whose roles were probed by mutagenesis both in vitro and in vivo. As p22/p18 contains only one of two conserved domains required for retroelement Gag assembly, they propose that p22/p18-Gag interactions block the Ty1 virus-like particle assembly pathway, resulting in defective particles incapable of supporting retrotransposition.

    • Matthew A. Cottee
    • , Sean L. Beckwith
    •  & Ian A. Taylor
  • Article
    | Open Access

    Mobile element insertions (MEIs) are a source of repetitive genetic variation and can lead to genetic disorders. Here the authors use Cas9-targeted nanopore sequencing to efficiently saturate enrichment for known and non-reference MEIs.

    • Torrin L. McDonald
    • , Weichen Zhou
    •  & Alan P. Boyle
  • Article
    | Open Access

    Human Long INterspersed Element class 1 (LINE-1) elements are expressed and mobilized in many types of cancer, contributing to malignancy. Here the authors show that the tumor suppressor microRNA let-7 targets the LINE-1 mRNA and reduces LINE-1 mobilization.

    • Pablo Tristán-Ramos
    • , Alejandro Rubio-Roldan
    •  & Sara R. Heras
  • Article
    | Open Access

    PiggyBac is a transposon used in genome engineering that does not leave excision footprints. Here the authors determine the structures of two complexes in which the piggyBac transposase is bound to DNA representing different steps of the transposition reaction, providing a basis for how the transposition reaction proceeds.

    • Qiujia Chen
    • , Wentian Luo
    •  & Fred Dyda
  • Article
    | Open Access

    In S. pombe, small non-coding RNA mediates heterochromatin formation by recruiting the nucleosome remodeling and histone deacetylase complex. Here, the authors show that fly nucleosome remodeler Mi-2 and histone deacetylase Rpd3 are involved in piRNA-dependent transcriptional silencing of transposable elements.

    • Bruno Mugat
    • , Simon Nicot
    •  & Séverine Chambeyron
  • Article
    | Open Access

    Mammals lose up to 80% of their finite oocyte supply during fetal development. Here the authors interrogate mechanisms of fetal oocyte attrition in mice, driven by the simultaneous upregulation of LINE-1 retrotransposon activity and inhibit these mechanisms to increase the functional ovarian reserve.

    • Marla E. Tharp
    • , Safia Malki
    •  & Alex Bortvin
  • Article
    | Open Access

    PIWI-interacting RNAs (piRNAs) are regulatory RNAs that bind to PIWI proteins to control transposons and maintain genome integrity. Here the authors characterized their binding specificity and reveal the 5′ nucleotide bias of the Drosophila Piwi protein, through mutation of its specificity loop.

    • Chad B. Stein
    • , Pavol Genzor
    •  & Astrid D. Haase
  • Article
    | Open Access

    Cytosine methyltransferases (DNMTs) often silence transposons in eukaryotic genomes. Here the authors describe the recurrent acquisition of DNMTs by transposons from two distantly-related eukaryotes and suggest that methylation of CG dinucleotides by transposon DNMTs could modify the host epigenome in dinoflagellates.

    • Alex de Mendoza
    • , Amandine Bonnet
    •  & Ryan Lister
  • Article
    | Open Access

    The declining performance of scale-up bioreactor cultures is commonly attributed to phenotypic and physical heterogeneities. Here, the authors reveal multiple recurring intra-pathway error modes that limit engineered E. coli mevalonic acid production over time- and industrial-scale fermentations.

    • Peter Rugbjerg
    • , Nils Myling-Petersen
    •  & Morten O. A. Sommer
  • Review Article
    | Open Access

    Transposable elements can be activated during germ cell maturation, potentially leading to genome instability and rewiring of the genetic circuitry. In this review, the authors discuss how the piRNA machinery suppresses these elements to ensure accurate spermatogenesis.

    • Christina Ernst
    • , Duncan T. Odom
    •  & Claudia Kutter
  • Article
    | Open Access

    Helitron elements are proposed rolling-circle transposons in eukaryotic genomes, but experimental evidence for their transposition has been lacking. Here, Grabundzija et al. reconstruct an active Helitron from bats which they name Helraiser, and characterize its mechanism of transposition in cell-free reactions and in human cell cultures in vitro.

    • Ivana Grabundzija
    • , Simon A. Messing
    •  & Zoltán Ivics
  • Article
    | Open Access

    The Microrchidia (Morc) family of GHKL ATPases are important repressors of transposons and other DNA-methylated and silent genes in A. thaliana. Here, the authors show that MORC1 is responsible for repression and methylation of specific classes of transposons in the mouse male germline.

    • William A. Pastor
    • , Hume Stroud
    •  & Steven E. Jacobsen
  • Article |

    SINEs are retrotransposons that insert exact copies of themselves into genomes. Using a marked copy of a SINE, Yadavet al. show that the sequences of newly transposed SINEs are a combination of marked and existing SINEs, suggesting a mechanism for the formation of mosaic SINEs.

    • Vijay Pal Yadav
    • , Prabhat Kumar Mandal
    •  & Sudha Bhattacharya