Type VI secretion apparatus and phage tail-associated protein complexes share a common evolutionary origin

Petr G. Leiman, Marek Basler, Udupi A. Ramagopal, Jeffrey B. Bonanno, J. Michael Sauder, Stefan Pukatzki, Stephen K. Burley, Steven C. Almo, John J. Mekalanos

Research output: Contribution to journalArticle

365 Scopus citations


Protein secretion is a common property of pathogenic microbes. Gram-negative bacterial pathogens use at least 6 distinct extracellular protein secretion systems to export proteins through their multilayered cell envelope and in some cases into host cells. Among the most widespread is the newly recognized Type VI secretion system (T6SS) which is composed of 15-20 proteins whose bio-chemical functionsare notwell understood. Using crystallographic, biochemical, and bioinformatic analyses, we identified 3 T6SS components, which are homologous to bacteriophage tail proteins. These include the tail tube protein; the membrane-penetrating needle, situated at the distal end of the tube; and another protein associated with the needle and tube. We propose thatT6SS is a multicomponent structure whose extracellular part resembles both structurally and functionally a bacteriophage tail, an efficient machine that translocates proteins and DNA across lipid membranes into cells.

Original languageEnglish (US)
Pages (from-to)4154-4159
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number11
StatePublished - Mar 17 2009



  • Bacteriophage
  • Membrane
  • Nanomachine
  • Translocation
  • Virulence

ASJC Scopus subject areas

  • General

Cite this