Temperature-regulated Efflux pump/potassium Antiporter System Mediates Resistance to Cationic Antimicrobial Peptides in Yersinia

Mol Microbiol. 2000 Jul;37(1):67-80. doi: 10.1046/j.1365-2958.2000.01956.x.


Most bacterial pathogens are resistant to cationic antimicrobial peptides (CAMPs) that are key components of the innate immunity of both vertebrates and invertebrates. In Gram-negative bacteria, the known CAMPs resistance mechanisms involve outer membrane (OM) modifications and specifically those in the lipopolysaccharide (LPS) molecule. Here we report, the characterization of a novel CAMPs resistance mechanism present in Yersinia that is dependent on an efflux pump/potassium antiporter system formed by the RosA and RosB proteins. The RosA/RosB system is activated by a temperature shift to 37 degrees C, but is also induced by the presence of the CAMPs, such as polymyxin B. This is the first report of a CAMPs resistance system that is induced by the presence of CAMPs. It is proposed that the RosA/RosB system protects the bacteria by both acidifying the cytoplasm to prevent the CAMPs action and pumping the CAMPs out of the cell.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Antimicrobial Cationic Peptides
  • Antiporters / genetics
  • Antiporters / metabolism*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Biological Transport, Active
  • Cations / metabolism
  • Drug Resistance, Microbial
  • Gene Expression Regulation, Bacterial
  • Genetic Complementation Test
  • Microbial Sensitivity Tests
  • Mutation
  • Polymyxin B / pharmacology
  • Potassium / metabolism*
  • Proteins / pharmacology*
  • Temperature
  • Yersinia / drug effects*
  • Yersinia / genetics
  • Yersinia / growth & development
  • Yersinia / metabolism


  • Anti-Bacterial Agents
  • Antimicrobial Cationic Peptides
  • Antiporters
  • Bacterial Proteins
  • Cations
  • Proteins
  • Polymyxin B
  • Potassium