<italic toggle="yes">In Vivo</italic> Biotinylation of the <italic toggle="yes">Toxoplasma</italic> Parasitophorous Vacuole Reveals Novel Dense Granule Proteins Important for Parasite Growth and Pathogenesis

ABSTRACT Toxoplasma gondii is an obligate intracellular parasite that invades host cells and replicates within a unique parasitophorous vacuole. To maintain this intracellular niche, the parasite secretes an array of dense granule proteins (GRAs) into the nascent parasitophorous vacuole. These GRAs...

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Autores principales:	Santhosh M. Nadipuram, Elliot W. Kim, Ajay A. Vashisht, Andrew H. Lin, Hannah N. Bell, Isabelle Coppens, James A. Wohlschlegel, Peter J. Bradley
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2016
Materias:	Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/878670a0ee27417388f783391b333fac
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spelling	oai:doaj.org-article:878670a0ee27417388f783391b333fac2021-11-15T15:50:18Z<italic toggle="yes">In Vivo</italic> Biotinylation of the <italic toggle="yes">Toxoplasma</italic> Parasitophorous Vacuole Reveals Novel Dense Granule Proteins Important for Parasite Growth and Pathogenesis10.1128/mBio.00808-162150-7511https://doaj.org/article/878670a0ee27417388f783391b333fac2016-09-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.00808-16https://doaj.org/toc/2150-7511ABSTRACT Toxoplasma gondii is an obligate intracellular parasite that invades host cells and replicates within a unique parasitophorous vacuole. To maintain this intracellular niche, the parasite secretes an array of dense granule proteins (GRAs) into the nascent parasitophorous vacuole. These GRAs are believed to play key roles in vacuolar remodeling, nutrient uptake, and immune evasion while the parasite is replicating within the host cell. Despite the central role of GRAs in the Toxoplasma life cycle, only a subset of these proteins have been identified, and many of their roles have not been fully elucidated. In this report, we utilize the promiscuous biotin ligase BirA* to biotinylate GRA proteins secreted into the vacuole and then identify those proteins by affinity purification and mass spectrometry. Using GRA-BirA* fusion proteins as bait, we have identified a large number of known and candidate GRAs and verified localization of 13 novel GRA proteins by endogenous gene tagging. We proceeded to functionally characterize three related GRAs from this group (GRA38, GRA39, and GRA40) by gene knockout. While Δgra38 and Δgra40 parasites showed no altered phenotype, disruption of GRA39 results in slow-growing parasites that contain striking lipid deposits in the parasitophorous vacuole, suggesting a role in lipid regulation that is important for parasite growth. In addition, parasites lacking GRA39 showed dramatically reduced virulence and a lower tissue cyst burden in vivo. Together, the findings from this work reveal a partial vacuolar proteome of T. gondii and identify a novel GRA that plays a key role in parasite replication and pathogenesis. IMPORTANCE Most intracellular pathogens reside inside a membrane-bound vacuole within their host cell that is extensively modified by the pathogen to optimize intracellular growth and avoid host defenses. In Toxoplasma, this vacuole is modified by a host of secretory GRA proteins, many of which remain unidentified. Here we demonstrate that in vivo biotinylation of proximal and interacting proteins using the promiscuous biotin ligase BirA* is a powerful approach to rapidly identify vacuolar GRA proteins. We further demonstrate that one factor identified by this approach, GRA39, plays an important role in the ability of the parasite to replicate within its host cell and cause disease.Santhosh M. NadipuramElliot W. KimAjay A. VashishtAndrew H. LinHannah N. BellIsabelle CoppensJames A. WohlschlegelPeter J. BradleyAmerican Society for MicrobiologyarticleMicrobiologyQR1-502ENmBio, Vol 7, Iss 4 (2016)
institution	DOAJ
collection	DOAJ
language	EN
topic	Microbiology QR1-502
spellingShingle	Microbiology QR1-502 Santhosh M. Nadipuram Elliot W. Kim Ajay A. Vashisht Andrew H. Lin Hannah N. Bell Isabelle Coppens James A. Wohlschlegel Peter J. Bradley <italic toggle="yes">In Vivo</italic> Biotinylation of the <italic toggle="yes">Toxoplasma</italic> Parasitophorous Vacuole Reveals Novel Dense Granule Proteins Important for Parasite Growth and Pathogenesis
description	ABSTRACT Toxoplasma gondii is an obligate intracellular parasite that invades host cells and replicates within a unique parasitophorous vacuole. To maintain this intracellular niche, the parasite secretes an array of dense granule proteins (GRAs) into the nascent parasitophorous vacuole. These GRAs are believed to play key roles in vacuolar remodeling, nutrient uptake, and immune evasion while the parasite is replicating within the host cell. Despite the central role of GRAs in the Toxoplasma life cycle, only a subset of these proteins have been identified, and many of their roles have not been fully elucidated. In this report, we utilize the promiscuous biotin ligase BirA* to biotinylate GRA proteins secreted into the vacuole and then identify those proteins by affinity purification and mass spectrometry. Using GRA-BirA* fusion proteins as bait, we have identified a large number of known and candidate GRAs and verified localization of 13 novel GRA proteins by endogenous gene tagging. We proceeded to functionally characterize three related GRAs from this group (GRA38, GRA39, and GRA40) by gene knockout. While Δgra38 and Δgra40 parasites showed no altered phenotype, disruption of GRA39 results in slow-growing parasites that contain striking lipid deposits in the parasitophorous vacuole, suggesting a role in lipid regulation that is important for parasite growth. In addition, parasites lacking GRA39 showed dramatically reduced virulence and a lower tissue cyst burden in vivo. Together, the findings from this work reveal a partial vacuolar proteome of T. gondii and identify a novel GRA that plays a key role in parasite replication and pathogenesis. IMPORTANCE Most intracellular pathogens reside inside a membrane-bound vacuole within their host cell that is extensively modified by the pathogen to optimize intracellular growth and avoid host defenses. In Toxoplasma, this vacuole is modified by a host of secretory GRA proteins, many of which remain unidentified. Here we demonstrate that in vivo biotinylation of proximal and interacting proteins using the promiscuous biotin ligase BirA* is a powerful approach to rapidly identify vacuolar GRA proteins. We further demonstrate that one factor identified by this approach, GRA39, plays an important role in the ability of the parasite to replicate within its host cell and cause disease.
format	article
author	Santhosh M. Nadipuram Elliot W. Kim Ajay A. Vashisht Andrew H. Lin Hannah N. Bell Isabelle Coppens James A. Wohlschlegel Peter J. Bradley
author_facet	Santhosh M. Nadipuram Elliot W. Kim Ajay A. Vashisht Andrew H. Lin Hannah N. Bell Isabelle Coppens James A. Wohlschlegel Peter J. Bradley
author_sort	Santhosh M. Nadipuram
title	<italic toggle="yes">In Vivo</italic> Biotinylation of the <italic toggle="yes">Toxoplasma</italic> Parasitophorous Vacuole Reveals Novel Dense Granule Proteins Important for Parasite Growth and Pathogenesis
title_short	<italic toggle="yes">In Vivo</italic> Biotinylation of the <italic toggle="yes">Toxoplasma</italic> Parasitophorous Vacuole Reveals Novel Dense Granule Proteins Important for Parasite Growth and Pathogenesis
title_full	<italic toggle="yes">In Vivo</italic> Biotinylation of the <italic toggle="yes">Toxoplasma</italic> Parasitophorous Vacuole Reveals Novel Dense Granule Proteins Important for Parasite Growth and Pathogenesis
title_fullStr	<italic toggle="yes">In Vivo</italic> Biotinylation of the <italic toggle="yes">Toxoplasma</italic> Parasitophorous Vacuole Reveals Novel Dense Granule Proteins Important for Parasite Growth and Pathogenesis
title_full_unstemmed	<italic toggle="yes">In Vivo</italic> Biotinylation of the <italic toggle="yes">Toxoplasma</italic> Parasitophorous Vacuole Reveals Novel Dense Granule Proteins Important for Parasite Growth and Pathogenesis
title_sort	<italic toggle="yes">in vivo</italic> biotinylation of the <italic toggle="yes">toxoplasma</italic> parasitophorous vacuole reveals novel dense granule proteins important for parasite growth and pathogenesis
publisher	American Society for Microbiology
publishDate	2016
url	https://doaj.org/article/878670a0ee27417388f783391b333fac
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<italic toggle="yes">In Vivo</italic> Biotinylation of the <italic toggle="yes">Toxoplasma</italic> Parasitophorous Vacuole Reveals Novel Dense Granule Proteins Important for Parasite Growth and Pathogenesis

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