DNA topology and adaptation of Salmonella typhimurium to an intracellular environment

David G. Marshall, Frances Bowe, Christine Hale, Gordon Dougan, Charles J. Dorman

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22 Citations (Scopus)


The expression of genes coding for determinants of DNA topology in the facultative intracellular pathogen Salmonella typhimurium was studied during adaptation by the bacteria to the intracellular environment of J774A.1 macrophage-like cells. A reporter plasmid was used to monitor changes in DNA supercoiling during intracellular growth. Induction of the dps and spv genes, previously shown to be induced in the macrophage, was detected, as was expression of genes coding for DNA gyrase, integration host factor and the nucleoid-associated protein H-NS. The topA gene, coding for the DNA relaxing enzyme topoisomerase I, was not induced. Reporter plasmid data showed that bacterial DNA became relaxed following uptake of S. typhimurium cells by the macrophage. These data indicate that DNA topology in S. typhimurium undergoes significant changes during adaptation to the intracellular environment. A model describing how this process may operate is discussed.

Original languageEnglish
Pages (from-to)565-574
Number of pages10
JournalPhilosophical Transactions of the Royal Society B: Biological Sciences
Issue number1397
Publication statusPublished - 29 May 2000
Externally publishedYes


  • Adaptation
  • DNA topology
  • Gene expression
  • Intracellular growth
  • Salmonella typhimurium

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