Completion of LINE integration involves an open '4-way' branched DNA intermediate

Nucleic Acids Res. 2019 Sep 19;47(16):8708-8719. doi: 10.1093/nar/gkz673.


Long Interspersed Elements (LINEs), also known as non-LTR retrotransposons, encode a multifunctional protein that reverse transcribes its mRNA into DNA at the site of insertion by target primed reverse transcription. The second half of the integration reaction remains very poorly understood. Second-strand DNA cleavage and second-strand DNA synthesis were investigated in vitro using purified components from a site-specific restriction-like endonuclease (RLE) bearing LINE. DNA structure was shown to be a critical component of second-strand DNA cleavage. A hitherto unknown and unexplored integration intermediate, an open '4-way' DNA junction, was recognized by the element protein and cleaved in a Holliday junction resolvase-like reaction. Cleavage of the 4-way junction resulted in a natural primer-template pairing used for second-strand DNA synthesis. A new model for RLE LINE integration is presented.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bombyx / genetics
  • Bombyx / metabolism
  • DNA / chemistry
  • DNA / genetics
  • DNA / metabolism
  • DNA Cleavage
  • DNA Primers / genetics
  • DNA Primers / metabolism
  • DNA Restriction Enzymes / genetics*
  • DNA Restriction Enzymes / metabolism
  • DNA, Cruciform / chemistry
  • DNA, Cruciform / genetics*
  • DNA, Cruciform / metabolism
  • Holliday Junction Resolvases / genetics
  • Holliday Junction Resolvases / metabolism
  • Long Interspersed Nucleotide Elements*
  • Nucleic Acid Conformation
  • RNA, Messenger / genetics*
  • RNA, Messenger / metabolism
  • RNA-Directed DNA Polymerase / genetics*
  • RNA-Directed DNA Polymerase / metabolism
  • Reverse Transcription*


  • DNA Primers
  • DNA, Cruciform
  • RNA, Messenger
  • DNA
  • RNA-Directed DNA Polymerase
  • DNA Restriction Enzymes
  • Holliday Junction Resolvases