The Coxiella burnetii cryptic plasmid is enriched in genes encoding type IV secretion system substrates.
J Bacteriol
; 193(7): 1493-503, 2011 Apr.
Article
en En
| MEDLINE
| ID: mdl-21216993
The intracellular bacterial pathogen Coxiella burnetii directs biogenesis of a phagolysosome-like parasitophorous vacuole (PV), in which it replicates. The organism encodes a Dot/Icm type IV secretion system (T4SS) predicted to deliver to the host cytosol effector proteins that mediate PV formation and other cellular events. All C. burnetii isolates carry a large, autonomously replicating plasmid or have chromosomally integrated plasmid-like sequences (IPS), suggesting that plasmid and IPS genes are critical for infection. Bioinformatic analyses revealed two candidate Dot/Icm substrates with eukaryotic-like motifs uniquely encoded by the QpH1 plasmid from the Nine Mile reference isolate. CpeC, containing an F-box domain, and CpeD, possessing kinesin-related and coiled-coil regions, were secreted by the closely related Legionella pneumophila Dot/Icm T4SS. An additional QpH1-specific gene, cpeE, situated in a predicted operon with cpeD, also encoded a secreted effector. Further screening revealed that three hypothetical proteins (CpeA, CpeB, and CpeF) encoded by all C. burnetii plasmids and IPS are Dot/Icm substrates. By use of new genetic tools, secretion of plasmid effectors by C. burnetii during host cell infection was confirmed using ß-lactamase and adenylate cyclase translocation assays, and a C-terminal secretion signal was identified. When ectopically expressed in HeLa cells, plasmid effectors trafficked to different subcellular sites, including autophagosomes (CpeB), ubiquitin-rich compartments (CpeC), and the endoplasmic reticulum (CpeD). Collectively, these results suggest that C. burnetii plasmid-encoded T4SS substrates play important roles in subversion of host cell functions, providing a plausible explanation for the absolute maintenance of plasmid genes by this pathogen.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Plásmidos
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Proteínas Bacterianas
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Regulación Bacteriana de la Expresión Génica
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Coxiella burnetii
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Sistemas de Secreción Bacterianos
Límite:
Humans
Idioma:
En
Revista:
J Bacteriol
Año:
2011
Tipo del documento:
Article
País de afiliación:
Estados Unidos
Pais de publicación:
Estados Unidos