Biological Diversity and Evolution of Type IV Secretion Systems

  • Peter J. ChristieEmail author
  • Laura Gomez Valero
  • Carmen Buchrieser
Part of the Current Topics in Microbiology and Immunology book series (CT MICROBIOLOGY, volume 413)


The bacterial type IV secretion systems (T4SSs) are a highly functionally and structurally diverse superfamily of secretion systems found in many species of Gram-negative and -positive bacteria. Collectively, the T4SSs can translocate DNA and monomeric and multimeric protein substrates to a variety of bacterial and eukaryotic cell types. Detailed phylogenomics analyses have established that the T4SSs evolved from ancient conjugation machines whose original functions were to disseminate mobile DNA elements within and between bacterial species. How members of the T4SS superfamily evolved to recognize and translocate specific substrate repertoires to prokaryotic or eukaryotic target cells is a fascinating question from evolutionary, biological, and structural perspectives. In this chapter, we will summarize recent findings that have shaped our current view of the biological diversity of the T4SSs. We focus mainly on two subtypes, designated as the types IVA (T4ASS) and IVB (T4BSS) systems that respectively are represented by the paradigmatic Agrobacterium tumefaciens VirB/VirD4 and Legionella pneumophila Dot/Icm T4SSs. We present current information about the composition and architectures of these representative systems. We also describe how these and a few related T4ASS and T4BSS members evolved as specialized nanomachines through acquisition of novel domains or subunits, a process that ultimately generated extensive genetic and structural mosaicism among this secretion superfamily. Finally, we present new phylogenomics information establishing that the T4BSSs are much more broadly distributed than initially envisioned.


Type IV secretion Conjugation DNA transfer Pathogenesis Effector translocation Legionella Dot/Icm Coupling protein Traffic ATPases 



Work in the Christie laboratory was supported by NIH grants R01GM48476 and R21AI105454. Work in the CB laboratory is financed by the Institut Pasteur, the grants N°ANR-10-LABX-62-IBEID, the Fondation pour la Recherche Médicale (FRM) grant N° DEQ 20120323697, and the Infect-ERA project EUGENPATH (ANR-13-IFEC-0003-02).


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Copyright information

© Springer International Publishing AG 2017

Authors and Affiliations

  • Peter J. Christie
    • 1
    Email author
  • Laura Gomez Valero
    • 2
    • 3
  • Carmen Buchrieser
    • 2
    • 3
  1. 1.Department of Microbiology and Molecular GeneticsMcGovern Medical SchoolHoustonUSA
  2. 2.Institut PasteurParisFrance
  3. 3.CNRS, UMR 3525ParisFrance

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