The Legionella IcmS-IcmW protein complex is important for Dot/Icm-mediated protein translocation

Shira Ninio, Deborah M. Zuckman-Cholon, Eric D. Cambronne, Craig R. Roy

Research output: Contribution to journalArticlepeer-review

119 Scopus citations


The intracellular pathogen Legionella pneumophila can infect and replicate within macrophages of a human host. To establish infection, Legionella require the Dot/Icm secretion system to inject protein substrates directly into the host cell cytoplasm. The mechanism by which substrate proteins are engaged and translocated by the Dot/Icm system is not well understood. Here we show that two cytosolic components of the Dot/Icm secretion machinery, the proteins IcmS and EcmW, play an important role in substrate translocation. Biochemical analysis indicates that IcmS and IcmW form a stable protein complex. In Legionella, the IcmW protein is rapidly degraded in the absence of the IcmS protein. Substrate proteins translocated into mammalian host cells by the Dot/Icm system were identified using the IcmW protein as bait in a yeast two-hybrid screen. It was determined that the IcmS-IcmW complex interacts with these substrates and plays an important role in translocation of these proteins into mammalian cells. These data are consistent with the IcmS-IcmW complex being involved in the recognition and Dot/ Icm-dependent translocation of substrate proteins during Legionella infection of host cells.

Original languageEnglish (US)
Pages (from-to)912-926
Number of pages15
JournalMolecular Microbiology
Issue number3
StatePublished - Feb 2005
Externally publishedYes

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology


Dive into the research topics of 'The Legionella IcmS-IcmW protein complex is important for Dot/Icm-mediated protein translocation'. Together they form a unique fingerprint.

Cite this