Effector Protein Cig2 Decreases Host Tolerance of Infection by Directing Constitutive Fusion of Autophagosomes with the <italic toggle="yes">Coxiella</italic>-Containing Vacuole

ABSTRACT Coxiella burnetii replicates in an acidified lysosome-derived vacuole. Biogenesis of the Coxiella-containing vacuole (CCV) requires bacterial effector proteins delivered into host cells by the Dot/Icm secretion system. Genetic and cell biological analysis revealed that an effector protein c...

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Main Authors: Lara J. Kohler, Shawna R. Reed, Shireen A. Sarraf, David D. Arteaga, Hayley J. Newton, Craig R. Roy
Format: Article
Language:English
Published: American Society for Microbiology 2016-09-01
Series:mBio
Online Access:https://journals.asm.org/doi/10.1128/mBio.01127-16
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author Lara J. Kohler
Shawna R. Reed
Shireen A. Sarraf
David D. Arteaga
Hayley J. Newton
Craig R. Roy
author_facet Lara J. Kohler
Shawna R. Reed
Shireen A. Sarraf
David D. Arteaga
Hayley J. Newton
Craig R. Roy
author_sort Lara J. Kohler
collection DOAJ
description ABSTRACT Coxiella burnetii replicates in an acidified lysosome-derived vacuole. Biogenesis of the Coxiella-containing vacuole (CCV) requires bacterial effector proteins delivered into host cells by the Dot/Icm secretion system. Genetic and cell biological analysis revealed that an effector protein called Cig2 promotes constitutive fusion of autophagosomes with the CCV to maintain this compartment in an autolysosomal stage of maturation. This distinguishes the CCV from other pathogen-containing vacuoles that are targeted by the host autophagy pathway, which typically confers host resistance to infection by delivering the pathogen to a toxic lysosomal environment. By maintaining the CCV in an autolysosomal stage of maturation, Cig2 enabled CCV homotypic fusion and enhanced bacterial virulence in the Galleria mellonella (wax moth) model of infection by a mechanism that decreases host tolerance. Thus, C. burnetii residence in an autolysosomal organelle alters host tolerance of infection, which indicates that Cig2-dependent manipulation of a lysosome-derived vacuole influences the host response to infection. IMPORTANCE Coxiella burnetii is an obligate, intracellular bacterial pathogen that replicates inside a unique, lysosome-like compartment called the Coxiella-containing vacuole (CCV). Over 130 bacterial effector proteins are delivered into the host cell cytosol by the C. burnetii Dot/Icm type IV secretion system. Although the Dot/Icm system is essential for pathogenesis, the functions of most effectors remain unknown. Here we show that the effector protein Cig2 is essential for converting the CCV to an organelle that is similar to the autolysosome. Cig2 function promotes constitutive fusion between the CCV and autophagosomes generated by selective autophagy. Cig2-directed biogenesis of an autolysosomal vacuole is essential for the unique fusogenic properties of the CCV and for virulence in an animal model of disease. This work highlights how bacterial subversion of the host autophagy pathway can influence the cell biological properties of the CCV and influence the host response to infection.
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spelling doaj.art-8bb47c6794e64fadac548e48b9bdf8462022-12-21T23:37:13ZengAmerican Society for MicrobiologymBio2150-75112016-09-017410.1128/mBio.01127-16Effector Protein Cig2 Decreases Host Tolerance of Infection by Directing Constitutive Fusion of Autophagosomes with the <italic toggle="yes">Coxiella</italic>-Containing VacuoleLara J. Kohler0Shawna R. Reed1Shireen A. Sarraf2David D. Arteaga3Hayley J. Newton4Craig R. Roy5Department of Microbial Pathogenesis, Boyer Center for Molecular Medicine, Yale University School of Medicine, New Haven, Connecticut, USADepartment of Microbial Pathogenesis, Boyer Center for Molecular Medicine, Yale University School of Medicine, New Haven, Connecticut, USABiochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USADepartment of Microbial Pathogenesis, Boyer Center for Molecular Medicine, Yale University School of Medicine, New Haven, Connecticut, USADepartment of Microbiology and Immunology, University of Melbourne, at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, AustraliaDepartment of Microbial Pathogenesis, Boyer Center for Molecular Medicine, Yale University School of Medicine, New Haven, Connecticut, USAABSTRACT Coxiella burnetii replicates in an acidified lysosome-derived vacuole. Biogenesis of the Coxiella-containing vacuole (CCV) requires bacterial effector proteins delivered into host cells by the Dot/Icm secretion system. Genetic and cell biological analysis revealed that an effector protein called Cig2 promotes constitutive fusion of autophagosomes with the CCV to maintain this compartment in an autolysosomal stage of maturation. This distinguishes the CCV from other pathogen-containing vacuoles that are targeted by the host autophagy pathway, which typically confers host resistance to infection by delivering the pathogen to a toxic lysosomal environment. By maintaining the CCV in an autolysosomal stage of maturation, Cig2 enabled CCV homotypic fusion and enhanced bacterial virulence in the Galleria mellonella (wax moth) model of infection by a mechanism that decreases host tolerance. Thus, C. burnetii residence in an autolysosomal organelle alters host tolerance of infection, which indicates that Cig2-dependent manipulation of a lysosome-derived vacuole influences the host response to infection. IMPORTANCE Coxiella burnetii is an obligate, intracellular bacterial pathogen that replicates inside a unique, lysosome-like compartment called the Coxiella-containing vacuole (CCV). Over 130 bacterial effector proteins are delivered into the host cell cytosol by the C. burnetii Dot/Icm type IV secretion system. Although the Dot/Icm system is essential for pathogenesis, the functions of most effectors remain unknown. Here we show that the effector protein Cig2 is essential for converting the CCV to an organelle that is similar to the autolysosome. Cig2 function promotes constitutive fusion between the CCV and autophagosomes generated by selective autophagy. Cig2-directed biogenesis of an autolysosomal vacuole is essential for the unique fusogenic properties of the CCV and for virulence in an animal model of disease. This work highlights how bacterial subversion of the host autophagy pathway can influence the cell biological properties of the CCV and influence the host response to infection.https://journals.asm.org/doi/10.1128/mBio.01127-16
spellingShingle Lara J. Kohler
Shawna R. Reed
Shireen A. Sarraf
David D. Arteaga
Hayley J. Newton
Craig R. Roy
Effector Protein Cig2 Decreases Host Tolerance of Infection by Directing Constitutive Fusion of Autophagosomes with the <italic toggle="yes">Coxiella</italic>-Containing Vacuole
mBio
title Effector Protein Cig2 Decreases Host Tolerance of Infection by Directing Constitutive Fusion of Autophagosomes with the <italic toggle="yes">Coxiella</italic>-Containing Vacuole
title_full Effector Protein Cig2 Decreases Host Tolerance of Infection by Directing Constitutive Fusion of Autophagosomes with the <italic toggle="yes">Coxiella</italic>-Containing Vacuole
title_fullStr Effector Protein Cig2 Decreases Host Tolerance of Infection by Directing Constitutive Fusion of Autophagosomes with the <italic toggle="yes">Coxiella</italic>-Containing Vacuole
title_full_unstemmed Effector Protein Cig2 Decreases Host Tolerance of Infection by Directing Constitutive Fusion of Autophagosomes with the <italic toggle="yes">Coxiella</italic>-Containing Vacuole
title_short Effector Protein Cig2 Decreases Host Tolerance of Infection by Directing Constitutive Fusion of Autophagosomes with the <italic toggle="yes">Coxiella</italic>-Containing Vacuole
title_sort effector protein cig2 decreases host tolerance of infection by directing constitutive fusion of autophagosomes with the italic toggle yes coxiella italic containing vacuole
url https://journals.asm.org/doi/10.1128/mBio.01127-16
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