Molecular and General Genetics MGG

, Volume 204, Issue 2, pp 322–327

In vivo loss of supercoiled DNA carrying a palindromic sequence

  • David Leach
  • Janet Lindsey

DOI: 10.1007/BF00425517

Cite this article as:
Leach, D. & Lindsey, J. Molec. Gen. Genet. (1986) 204: 322. doi:10.1007/BF00425517


Interest in the fate of long palindromic DNA sequences in E. coli has been kindled by the observation that their inviability is overcome in recBC sbcB strains and that these hosts permit the construction of DNA libraries containing long palindromic sequences present in the human genome. In this paper we show that a reduction in the level of intracellular supercoiled DNA occurs as the result of the presence of a 530 bp palindrome in bacteriophage lambda. This reduction occurs in Rec+ and recA strains but not in strains lacking exonucleases V and I (recBC sbcB). However, the DNA must be active (not repressed) for this reduction to be observed, since it is not seen in a Rec+ host lysogenic for phage lambda. These results argue against two hypotheses: firstly, that the palindrome causes inviability solely by interfering with packaging, and secondly, that it dose so solely by interfering with recombination. Conversely, these results suggest that a feature of active monomeric DNA (probably its replication) is involved in inviability.

Key words

Palindrome Lambda recBC sbcB E. coli 

Copyright information

© Springer-Verlag 1986

Authors and Affiliations

  • David Leach
    • 1
  • Janet Lindsey
    • 1
  1. 1.Department of Molecular BiologyUniversity of EdinburghEdinburghUK

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