Pathogenic adaptation of intracellular bacteria by rewiring a cis-regulatory input function Academic Article uri icon

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  • The acquisition of DNA by horizontal gene transfer enables bacteria to adapt to previously unexploited ecological niches. Although horizontal gene transfer and mutation of protein-coding sequences are well-recognized forms of pathogen evolution, the evolutionary significance of cis-regulatory mutations in creating phenotypic diversity through altered transcriptional outputs is not known. We show the significance of regulatory mutation for pathogen evolution by mapping and then rewiring a cis-regulatory module controlling a gene required for murine typhoid. Acquisition of a binding site for the Salmonella pathogenicity island-2 regulator, SsrB, enabled the srfN gene, ancestral to the Salmonella genus, to play a role in pathoadaptation of S. typhimurium to a host animal. We identified the evolved cis-regulatory module and quantified the fitness gain that this regulatory output accrues for the bacterium using competitive infections of host animals. Our findings highlight a mechanism of pathogen evolution involving regulatory mutation that is selected because of the fitness advantage the new regulatory output provides the incipient clones.


  • Osborne, SE
  • Walthers, D
  • Tomljenovic, AM
  • Mulder, DT
  • Silphaduang, U
  • Duong, N
  • Lowden, MJ
  • Wickham, ME
  • Waller, RF
  • Kenney, LJ
  • Coombes, Brian

publication date

  • March 10, 2009