Altered directionality in the Cre-loxP site-specific recombination pathway

Manuel Aranda, Chryssa Kanellopoulou, Nicole Christ, Michael Peitz, Klaus Rajewsky, Peter Dröge*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


The site-specific recombinase Cre must employ control mechanisms to impose directionality on recombination. When two recombination sites (locus of crossing over in phage P1, loxP) are placed as direct repeats on the same DNA molecule, collision between loxP-bound Cre dimers leads to excision of intervening DNA. If two sites are placed as inverted repeats, the intervening segment is flipped around. Cre catalyzes these reactions in the absence of protein co-factors. Current models suggest that directionality is controlled at two steps in the recombination pathway: the juxtaposition of loxP sites and the single-strand-transfer reactions within the synaptic complex. Here, we show that in Escherichia coli strain 294-Cre, directionality for recombination is altered when the expression of Cre is increased. This leads to deletion instead of inversion on substrates carrying two loxP sites as inverted repeats. The nucleotide sequence composition of loxP sites remaining in aberrant products indicates that site alignment and/or DNA strand transfer in the in vivo Cre-loxP recombination pathway are not always tightly controlled.

Original languageEnglish (US)
Pages (from-to)453-459
Number of pages7
JournalJournal of molecular biology
Issue number3
StatePublished - Aug 17 2001
Externally publishedYes


  • Cre
  • Site alignment
  • Site-specific recombination
  • Strand exchange
  • Synaptic complex

ASJC Scopus subject areas

  • Molecular Biology
  • Structural Biology


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