Abstract
| Original language | English |
|---|---|
| Pages (from-to) | 3290-3304 |
| Number of pages | 15 |
| Journal | Infection and Immunity |
| Volume | 75 |
| Issue number | 7 |
| Early online date | 16 Apr 2007 |
| DOIs | |
| Publication status | Published - Jul 2007 |
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Keywords
- Macrophages
- Microscopy, Confocal
- Animals
- Legionella pneumophila
- Carrier Proteins
- Humans
- Phagosomes
- Membrane Proteins
- Acanthamoeba
- Bacterial Proteins
- Epithelial Cells
- Cytosol
- Time Factors
- Mutation
- U937 Cells
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Rapid escape of the dot/icm mutants of Legionella pneumophila into the cytosol of mammalian and protozoan cells. / Molmeret, Maëlle; Santic', Marina; Asare, Rexford; Carabeo, Reynold A. ; Abu Kwaik, Yousef.
In: Infection and Immunity, Vol. 75, No. 7, 07.2007, p. 3290-3304.Research output: Contribution to journal › Article
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TY - JOUR
T1 - Rapid escape of the dot/icm mutants of Legionella pneumophila into the cytosol of mammalian and protozoan cells
AU - Molmeret, Maëlle
AU - Santic', Marina
AU - Asare, Rexford
AU - Carabeo, Reynold A.
AU - Abu Kwaik, Yousef
PY - 2007/7
Y1 - 2007/7
N2 - The Legionella pneumophila-containing phagosome evades endocytic fusion and intercepts endoplasmic reticulum (ER)-to-Golgi vesicle traffic, which is believed to be mediated by the Dot/Icm type IV secretion system. Although phagosomes harboring dot/icm mutants are thought to mature through the endosomal-lysosomal pathway, colocalization studies with lysosomal markers have reported contradictory results. In addition, phagosomes harboring the dot/icm mutants do not interact with endocytosed materials, which is inconsistent with maturation of the phagosomes in the endosomal-lysosomal pathway. Using multiple strategies, we show that the dot/icm mutants defective in the Dot/Icm structural apparatus are unable to maintain the integrity of their phagosomes and escape into the cytoplasm within minutes of entry into various mammalian and protozoan cells in a process independent of the type II secretion system. In contrast, mutants defective in cytoplasmic chaperones of Dot/Icm effectors and rpoS, letA/S, and letE regulatory mutants are all localized within intact phagosomes. Importantly, non-dot/icm L. pneumophila mutants whose phagosomes acquire late endosomal-lysosomal markers are all located within intact phagosomes. Using high-resolution electron microscopy, we show that phagosomes harboring the dot/icm transporter mutants do not fuse to lysosomes but are free in the cytoplasm. Inhibition of ER-to-Golgi vesicle traffic by brefeldin A does not affect the integrity of the phagosomes harboring the parental strain of L. pneumophila. We conclude that the Dot/Icm transporter is involved in maintaining the integrity of the L. pneumophila phagosome, independent of interception of ER-to-Golgi vesicle traffic, which is a novel function of type IV secretion systems.
AB - The Legionella pneumophila-containing phagosome evades endocytic fusion and intercepts endoplasmic reticulum (ER)-to-Golgi vesicle traffic, which is believed to be mediated by the Dot/Icm type IV secretion system. Although phagosomes harboring dot/icm mutants are thought to mature through the endosomal-lysosomal pathway, colocalization studies with lysosomal markers have reported contradictory results. In addition, phagosomes harboring the dot/icm mutants do not interact with endocytosed materials, which is inconsistent with maturation of the phagosomes in the endosomal-lysosomal pathway. Using multiple strategies, we show that the dot/icm mutants defective in the Dot/Icm structural apparatus are unable to maintain the integrity of their phagosomes and escape into the cytoplasm within minutes of entry into various mammalian and protozoan cells in a process independent of the type II secretion system. In contrast, mutants defective in cytoplasmic chaperones of Dot/Icm effectors and rpoS, letA/S, and letE regulatory mutants are all localized within intact phagosomes. Importantly, non-dot/icm L. pneumophila mutants whose phagosomes acquire late endosomal-lysosomal markers are all located within intact phagosomes. Using high-resolution electron microscopy, we show that phagosomes harboring the dot/icm transporter mutants do not fuse to lysosomes but are free in the cytoplasm. Inhibition of ER-to-Golgi vesicle traffic by brefeldin A does not affect the integrity of the phagosomes harboring the parental strain of L. pneumophila. We conclude that the Dot/Icm transporter is involved in maintaining the integrity of the L. pneumophila phagosome, independent of interception of ER-to-Golgi vesicle traffic, which is a novel function of type IV secretion systems.
KW - Macrophages
KW - Microscopy, Confocal
KW - Animals
KW - Legionella pneumophila
KW - Carrier Proteins
KW - Humans
KW - Phagosomes
KW - Membrane Proteins
KW - Acanthamoeba
KW - Bacterial Proteins
KW - Epithelial Cells
KW - Cytosol
KW - Time Factors
KW - Mutation
KW - U937 Cells
U2 - 10.1128/IAI.00292-07
DO - 10.1128/IAI.00292-07
M3 - Article
C2 - 17438033
VL - 75
SP - 3290
EP - 3304
JO - Infection and Immunity
JF - Infection and Immunity
SN - 0019-9567
IS - 7
ER -