Making Home Sweet and Sturdy: <italic toggle="yes">Toxoplasma gondii</italic> ppGalNAc-Ts Glycosylate in Hierarchical Order and Confer Cyst Wall Rigidity

ABSTRACT The protozoan intracellular parasite Toxoplasma gondii forms latent cysts in the central nervous system (CNS) and persists for the lifetime of the host. This cyst is cloaked with a glycosylated structure called the cyst wall. Previously, we demonstrated that a mucin-like glycoprotein, CST1,...

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Autores principales:	Tadakimi Tomita, Tatsuki Sugi, Rama Yakubu, Vincent Tu, Yanfen Ma, Louis M. Weiss
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2017
Materias:	Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/397114ecca82431e89dc249ba1ba2d44
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spelling	oai:doaj.org-article:397114ecca82431e89dc249ba1ba2d442021-11-15T15:51:07ZMaking Home Sweet and Sturdy: <italic toggle="yes">Toxoplasma gondii</italic> ppGalNAc-Ts Glycosylate in Hierarchical Order and Confer Cyst Wall Rigidity10.1128/mBio.02048-162150-7511https://doaj.org/article/397114ecca82431e89dc249ba1ba2d442017-03-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.02048-16https://doaj.org/toc/2150-7511ABSTRACT The protozoan intracellular parasite Toxoplasma gondii forms latent cysts in the central nervous system (CNS) and persists for the lifetime of the host. This cyst is cloaked with a glycosylated structure called the cyst wall. Previously, we demonstrated that a mucin-like glycoprotein, CST1, localizes to the cyst wall and confers structural rigidity on brain cysts in a mucin-like domain-dependent manner. The mucin-like domain of CST1 is composed of 20 units of threonine-rich tandem repeats that are O-GalNAc glycosylated. A family of enzymes termed polypeptide N-acetylgalactosaminyltransferases (ppGalNAc-Ts) initiates O-GalNAc glycosylation. To identify which isoforms of ppGalNAc-Ts are responsible for the glycosylation of the CST1 mucin-like domain and to evaluate the function of each ppGalNAc-T in the overall glycosylation of the cyst wall, all five ppGalNAc-T isoforms were deleted individually from the T. gondii genome. The ppGalNAc-T2 and -T3 deletion mutants produced various glycosylation defects on the cyst wall, implying that many cyst wall glycoproteins are glycosylated by T2 and T3. Both T2 and T3 glycosylate the CST1 mucin-like domain, and this glycosylation is necessary for CST1 to confer structural rigidity on the cyst wall. We established that T2 is required for the initial glycosylation of the mucin-like domain and that T3 is responsible for the sequential glycosylation on neighboring acceptor sites, demonstrating hierarchical glycosylation by two distinct initiating and filling-in ppGalNAc-Ts in an intact organism. IMPORTANCE Toxoplasma gondii is an obligate intracellular parasite that infects a third of the world’s population. It can cause severe congenital disease and devastating encephalitis in immunocompromised individuals. We identified two glycosyltransferases, ppGalNAc-T2 and -T3, which are responsible for glycosylating cyst wall proteins in a hierarchical fashion. This glycosylation confers structural rigidity on the brain cyst. Our studies provide new insights into the mechanisms of O-GalNAc glycosylation in T. gondii.Tadakimi TomitaTatsuki SugiRama YakubuVincent TuYanfen MaLouis M. WeissAmerican Society for MicrobiologyarticleMicrobiologyQR1-502ENmBio, Vol 8, Iss 1 (2017)
institution	DOAJ
collection	DOAJ
language	EN
topic	Microbiology QR1-502
spellingShingle	Microbiology QR1-502 Tadakimi Tomita Tatsuki Sugi Rama Yakubu Vincent Tu Yanfen Ma Louis M. Weiss Making Home Sweet and Sturdy: <italic toggle="yes">Toxoplasma gondii</italic> ppGalNAc-Ts Glycosylate in Hierarchical Order and Confer Cyst Wall Rigidity
description	ABSTRACT The protozoan intracellular parasite Toxoplasma gondii forms latent cysts in the central nervous system (CNS) and persists for the lifetime of the host. This cyst is cloaked with a glycosylated structure called the cyst wall. Previously, we demonstrated that a mucin-like glycoprotein, CST1, localizes to the cyst wall and confers structural rigidity on brain cysts in a mucin-like domain-dependent manner. The mucin-like domain of CST1 is composed of 20 units of threonine-rich tandem repeats that are O-GalNAc glycosylated. A family of enzymes termed polypeptide N-acetylgalactosaminyltransferases (ppGalNAc-Ts) initiates O-GalNAc glycosylation. To identify which isoforms of ppGalNAc-Ts are responsible for the glycosylation of the CST1 mucin-like domain and to evaluate the function of each ppGalNAc-T in the overall glycosylation of the cyst wall, all five ppGalNAc-T isoforms were deleted individually from the T. gondii genome. The ppGalNAc-T2 and -T3 deletion mutants produced various glycosylation defects on the cyst wall, implying that many cyst wall glycoproteins are glycosylated by T2 and T3. Both T2 and T3 glycosylate the CST1 mucin-like domain, and this glycosylation is necessary for CST1 to confer structural rigidity on the cyst wall. We established that T2 is required for the initial glycosylation of the mucin-like domain and that T3 is responsible for the sequential glycosylation on neighboring acceptor sites, demonstrating hierarchical glycosylation by two distinct initiating and filling-in ppGalNAc-Ts in an intact organism. IMPORTANCE Toxoplasma gondii is an obligate intracellular parasite that infects a third of the world’s population. It can cause severe congenital disease and devastating encephalitis in immunocompromised individuals. We identified two glycosyltransferases, ppGalNAc-T2 and -T3, which are responsible for glycosylating cyst wall proteins in a hierarchical fashion. This glycosylation confers structural rigidity on the brain cyst. Our studies provide new insights into the mechanisms of O-GalNAc glycosylation in T. gondii.
format	article
author	Tadakimi Tomita Tatsuki Sugi Rama Yakubu Vincent Tu Yanfen Ma Louis M. Weiss
author_facet	Tadakimi Tomita Tatsuki Sugi Rama Yakubu Vincent Tu Yanfen Ma Louis M. Weiss
author_sort	Tadakimi Tomita
title	Making Home Sweet and Sturdy: <italic toggle="yes">Toxoplasma gondii</italic> ppGalNAc-Ts Glycosylate in Hierarchical Order and Confer Cyst Wall Rigidity
title_short	Making Home Sweet and Sturdy: <italic toggle="yes">Toxoplasma gondii</italic> ppGalNAc-Ts Glycosylate in Hierarchical Order and Confer Cyst Wall Rigidity
title_full	Making Home Sweet and Sturdy: <italic toggle="yes">Toxoplasma gondii</italic> ppGalNAc-Ts Glycosylate in Hierarchical Order and Confer Cyst Wall Rigidity
title_fullStr	Making Home Sweet and Sturdy: <italic toggle="yes">Toxoplasma gondii</italic> ppGalNAc-Ts Glycosylate in Hierarchical Order and Confer Cyst Wall Rigidity
title_full_unstemmed	Making Home Sweet and Sturdy: <italic toggle="yes">Toxoplasma gondii</italic> ppGalNAc-Ts Glycosylate in Hierarchical Order and Confer Cyst Wall Rigidity
title_sort	making home sweet and sturdy: <italic toggle="yes">toxoplasma gondii</italic> ppgalnac-ts glycosylate in hierarchical order and confer cyst wall rigidity
publisher	American Society for Microbiology
publishDate	2017
url	https://doaj.org/article/397114ecca82431e89dc249ba1ba2d44
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Making Home Sweet and Sturdy: <italic toggle="yes">Toxoplasma gondii</italic> ppGalNAc-Ts Glycosylate in Hierarchical Order and Confer Cyst Wall Rigidity

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