Document Detail


Host factors required for modulation of phagosome biogenesis and proliferation of Francisella tularensis within the cytosol.
MedLine Citation:
PMID:  20552012     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
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 approximately 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.
Authors:
Christine Akimana; Souhaila Al-Khodor; Yousef Abu Kwaik
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2010-06-11
Journal Detail:
Title:  PloS one     Volume:  5     ISSN:  1932-6203     ISO Abbreviation:  PLoS ONE     Publication Date:  2010  
Date Detail:
Created Date:  2010-06-16     Completed Date:  2010-09-01     Revised Date:  2013-05-29    
Medline Journal Info:
Nlm Unique ID:  101285081     Medline TA:  PLoS One     Country:  United States    
Other Details:
Languages:  eng     Pagination:  e11025     Citation Subset:  IM    
Affiliation:
Department of Microbiology and Immunology, College of Medicine, University of Louisville, Louisville, Kentucky, USA.
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MeSH Terms
Descriptor/Qualifier:
Animals
Cell Line
Cytosol / microbiology*
Drosophila melanogaster / physiology
Francisella tularensis / genetics,  growth & development*
Humans
Integration Host Factors / physiology*
Phagosomes / microbiology*
Phosphotransferases (Alcohol Group Acceptor) / physiology
RNA Interference
Thiolester Hydrolases / physiology
Grant Support
ID/Acronym/Agency:
R01AI069321/AI/NIAID NIH HHS; R01AI43965/AI/NIAID NIH HHS
Chemical
Reg. No./Substance:
0/Integration Host Factors; EC 2.7.1.-/Phosphotransferases (Alcohol Group Acceptor); EC 2.7.1.67/phosphatidylinositol phosphate 4-kinase; EC 3.1.2.-/Thiolester Hydrolases; EC 3.1.2.15/Usp22 protein, human
Comments/Corrections

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