Journal article
The Francisella O-antigen mediates survival in the macrophage cytosol via autophagy avoidance
Cellular microbiology, Vol.16(6), pp.862-877
06/2014
Handle:
https://hdl.handle.net/2376/116124
PMCID: PMC4028363
PMID: 24286610
Abstract
Autophagy is a key innate immune response to intracellular parasites that promotes their delivery to degradative lysosomes following detection in the cytosol or within damaged vacuoles. Like
Listeria
and
Shigella
, which use specific mechanisms to avoid autophagic detection and capture, the bacterial pathogen
Francisella tularensis
proliferates within the cytosol of macrophages without demonstrable control by autophagy. To examine how
Francisella
evades autophagy, we screened a library of
F. tularensis
subsp.
tularensis
Schu S4
HimarFT
transposon mutants in GFP-LC3-expressing murine macrophages by microscopy for clones localised within autophagic vacuoles after phagosomal escape. Eleven clones showed autophagic capture at six hours post-infection, whose
HimarFT
insertions clustered to four genetic loci involved in lipopolysaccharidic and capsular O-antigen biosynthesis. Consistent with the
HimarFT
mutants, in-frame deletion mutants of two representative loci, FTT1236 and FTT1448c (
manC
), lacking both LPS and capsular O-antigen, underwent phagosomal escape but were cleared from the host cytosol. Unlike wild type
Francisella
, the O-antigen deletion mutants were ubiquitinated, and recruited the autophagy adaptor p62/SQSTM1 and LC3 prior to cytosolic clearance. Autophagy-deficient macrophages partially supported replication of both mutants, indicating that O-antigen-lacking
Francisella
are controlled by autophagy. These data demonstrate the intracellular protective role of this bacterial surface polysaccharide against autophagy.
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Details
- Title
- The Francisella O-antigen mediates survival in the macrophage cytosol via autophagy avoidance
- Creators
- Elizabeth Di Russo Case - Laboratory of Intracellular Parasites, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USAAudrey Chong - Laboratory of Intracellular Parasites, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USATara D Wehrly - Laboratory of Intracellular Parasites, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USABryan Hansen - Electron Microscopy Unit, Research Technologies Branch, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USARobert Child - Laboratory of Intracellular Parasites, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USASeungmin Hwang - Department of Pathology and Immunology and Midwest Regional Center of Excellence for Biodefense and Emerging Infectious Diseases Research, Washington University School of Medicine, St Louis, MO 63110, USAHerbert W Virgin - Department of Pathology and Immunology and Midwest Regional Center of Excellence for Biodefense and Emerging Infectious Diseases Research, Washington University School of Medicine, St Louis, MO 63110, USAJean Celli - Laboratory of Intracellular Parasites, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA
- Publication Details
- Cellular microbiology, Vol.16(6), pp.862-877
- Academic Unit
- Paul G. Allen School for Global Animal Health
- Identifiers
- 99900548128801842
- Language
- English
- Resource Type
- Journal article