The Icm/Dot type-IV Secretion Systems of Legionella Pneumophila and Coxiella Burnetii

FEMS Microbiol Rev. 2005 Jan;29(1):65-81. doi: 10.1016/j.femsre.2004.07.001.


Type-IV secretion systems are devices present in a wide range of bacteria (including bacterial pathogens) that deliver macromolecules (proteins and single-strand-DNA) across kingdom barriers (as well as between bacteria and into the surroundings). The type-IV secretion systems were divided into two subgroups and Legionella pneumophila and Coxiella burnetii are the only two bacteria known today to utilize a type-IVB secretion system for pathogenesis. In this review we summarized the available information concerning the icm/dot type-IVB secretion systems by comparing the two bacteria that possess this system, the proteins components of their systems as well as the homology of proteins from type-IVB secretion systems to proteins from type-IVA secretion systems. In addition, the phenotypes associated with mutants in the L. pneumophila icm/dot genes, their relations to properties of specific Icm/Dot proteins as well as the protein substrates delivered by this system are described.

Publication types

  • Review

MeSH terms

  • Bacterial Proteins / genetics*
  • Bacterial Proteins / metabolism
  • Coxiella burnetii / genetics*
  • Coxiella burnetii / metabolism*
  • Coxiella burnetii / pathogenicity
  • Legionella pneumophila / genetics*
  • Legionella pneumophila / metabolism*
  • Legionella pneumophila / pathogenicity
  • Virulence


  • Bacterial Proteins