Host factors required for modulation of phagosome biogenesis and proliferation of francisella tularensis within the cytosol

Christine Akimana, Souhaila M. Al Khodor, Yousef Abu Kwaik

Research output: Contribution to journalArticle

45 Citations (Scopus)

Abstract

Francisella tularensis is a highly infectious facultative intracellular bacterium that can be transmitted between mammals by arthropod vectors. Similar to many other intracellular bacteria that replicate within the cytosol, such as Listeria, Shigella, Burkholderia, and Rickettsia, the virulence of F. tularensis depends on its ability to modulate biogenesis of its phagosome and to escape into the host cell cytosol where it proliferates. Recent studies have identified the F. tularensis genes required for modulation of phagosome biogenesis and escape into the host cell cytosol within human and arthropod-derived cells. However, the arthropod and mammalian host factors required for intracellular proliferation of F. tularensis are not known. We have utilized a forward genetic approach employing genome-wide RNAi screen in Drosophila melanogaster-derived cells. Screening a library of ~21,300 RNAi, we have identified at least 186 host factors required for intracellular bacterial proliferation. We silenced twelve mammalian homologues by RNAi in HEK293T cells and identified three conserved factors, the PI4 kinase PI4KCA, the ubiquitin hydrolase USP22, and the ubiquitin ligase CDC27, which are also required for replication in human cells. The PI4KCA and USP22 mammalian factors are not required for modulation of phagosome biogenesis or phagosomal escape but are required for proliferation within the cytosol. In contrast, the CDC27 ubiquitin ligase is required for evading lysosomal fusion and for phagosomal escape into the cytosol. Although F. tularensis interacts with the autophagy pathway during late stages of proliferation in mouse macrophages, this does not occur in human cells. Our data suggest that F. tularensis utilizes host ubiquitin turnover in distinct mechanisms during the phagosomal and cytosolic phases and phosphoinositide metabolism is essential for cytosolic proliferation of F. tularensis. Our data will facilitate deciphering molecular ecology, patho-adaptation of F. tularensis to the arthropod vector and its role in bacterial ecology and patho-evolution to infect mammals.

Original languageEnglish
Article numbere11025
JournalPLoS One
Volume5
Issue number6
DOIs
Publication statusPublished - 2010
Externally publishedYes

Fingerprint

Francisella tularensis
phagosomes
Phagosomes
Ubiquitin
cytosol
Cytosol
Modulation
Mammals
Ecology
Ligases
ubiquitin
arthropods
Bacteria
Arthropod Vectors
RNA Interference
Genes
Cells
Listeria
cells
Arthropods

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Medicine(all)

Cite this

Host factors required for modulation of phagosome biogenesis and proliferation of francisella tularensis within the cytosol. / Akimana, Christine; Al Khodor, Souhaila M.; Kwaik, Yousef Abu.

In: PLoS One, Vol. 5, No. 6, e11025, 2010.

Research output: Contribution to journalArticle

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