Search for the Presence of Lectin-Binding Sites on Toxoplasma gondii

Kk, Sethi; Rahman, Akm Anisur; Pelster, Bernd; Brandis, H.

doi:10.2307/3279850

Cited by 44 publications

(22 citation statements)

References 14 publications

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“…The most prominent staining pattern is that of the tissue cyst wall using Dolichos lectin (DBA; recognizing terminal GalNAc) (Fig. 1) [27, 30, 31]. The primary target being glycosylated with GalNAc, designated TgCST1 [32••], was identified by the Weiss group as a high molecular weight mucin that is expressed both in tachyzoite vacuoles and tissue cysts, but only substantially glycosylated in the tissue cyst form [32••].…”

Section: Organization Of the In Vivo Tissue Cystmentioning

confidence: 99%

Reexamining Chronic Toxoplasma gondii Infection: Surprising Activity for a “Dormant” Parasite

Sinai¹,

Watts

Dhara³

et al. 2016

Curr Clin Micro Rpt

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Purpose of Review Despite over a third of the world’s population being chronically infected with Toxoplasma gondii, little is known about this largely asymptomatic phase of infection. This stage is mediated in vivo by bradyzoites within tissue cysts. The absence of overt symptoms has been attributed to the dormancy of bradyzoites. In this review, we reexamine the conventional view of chronic toxoplasmosis in light of emerging evidence challenging both the nature of dormancy and the consequences of infection in the CNS. Recent Findings New and emerging data reveal a previously unrecognized level of physiological and replicative capacity of bradyzoites within tissue cysts. These findings have emerged in the context of a reexamination of the chronic infection in the brain that correlates with changes in neuronal architecture, neurochemistry, and behavior that suggest that the chronic infection is not without consequence. Summary The emerging data driven by the development of new approaches to study the progression of chronic toxoplasma infection reveals significant physiological and replicative capacity for what has been viewed as a dormant state. The emergence of bradyzoite and tissue cyst biology from what was viewed as a physiological “black box” offers exciting new areas for investigation with direct implications on the approaches to drug development targeting this drug-refractory state. In addition, new insights from studies on the neurobiology on chronic infection reveal a complex and dynamic interplay between the parasite, brain microenvironment, and the immune response that results in the detente that promotes the life-long persistence of the parasite in the host.

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Section: Organization Of the In Vivo Tissue Cystmentioning

confidence: 99%

Reexamining Chronic Toxoplasma gondii Infection: Surprising Activity for a “Dormant” Parasite

Sinai¹,

Watts

Dhara³

et al. 2016

Curr Clin Micro Rpt

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“…The cyst wall is modified with various glycans, and this is most likely due to posttranslational modifications occurring on various cyst wall proteins. Glycosylated cyst wall components are stained by periodic acid-Schiff (PAS) stain, which binds to carbohydrates, as well as various lectins, including Dolichos biflorus lectin (DBA), which binds to GalNAcα1-3GalNAc, and succinylated wheat germ lectin (s-WGA), which binds to terminal GlcNAc (7). Recently, characterized cyst wall proteins CST1 (TGME49_264660) and T. gondii proteophosphoglycan 1 (TgPPG1; TGME49_297520) have both been demonstrated to be glycosylated proteins (8, 9).…”

Section: Introductionmentioning

confidence: 99%

Making Home Sweet and Sturdy:Toxoplasma gondiippGalNAc-Ts Glycosylate in Hierarchical Order and Confer Cyst Wall Rigidity

Tomita

Sugi

Yakubu

et al. 2017

mBio

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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.

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“…Interestingly, a closely related apicomplexan, Toxoplasma gondi, is not agglutinated, nor does it bind any lectin tested (Sethi et al 1977;Handman et al 1980; Hoshino- Shimizu et al 1980). This information led many researchers to speculate that there was no carbohydrate on the surface of T. gondii, even though the surface is negatively charged (Cintra et al 1986).…”

Section: Discussionmentioning

confidence: 99%

Lectin-binding by sporozoites of Eimeria tenella

2002

Parasitol Res

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Sporozoites of Eimeria tenella were reacted in vitro with 19 different lectins characterized with a variety of carbohydrate-binding properties. Nine lectins caused sporozoite agglutination, which was inhibited by the specific carbohydrates mannose, sialic acid, melibiose, D-galactose, or D-galNAc. When intact live or fixed whole sporozoites were reacted with fluorescein isothiocyanate-conjugated lectins, another nine lectins bound to sporozoites, giving weak to strong fluorescence but not agglutination. Of these, all nine lectins bound to surface sites, but four also bound to the refractile body. Two of the agglutinating lectins also bound to intracellular organelles of air-dried sporozoites. SDS-PAGE analysis showed that biotinylated lectins bound a wide variety of parasite proteins. Lectins with similar carbohydrate specificities had some similarity in binding patterns of parasite proteins, as well as marked differences. In a few cases lectins with different carbohydrate specificities bound common protein bands. Only one lectin (Dolichos biflorus) showed no evidence of binding to whole sporozoites, organelles, or proteins.

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Search for the Presence of Lectin-Binding Sites on Toxoplasma gondii

Cited by 44 publications

References 14 publications

Reexamining Chronic Toxoplasma gondii Infection: Surprising Activity for a “Dormant” Parasite

Reexamining Chronic Toxoplasma gondii Infection: Surprising Activity for a “Dormant” Parasite

Making Home Sweet and Sturdy:Toxoplasma gondiippGalNAc-Ts Glycosylate in Hierarchical Order and Confer Cyst Wall Rigidity

Lectin-binding by sporozoites of Eimeria tenella

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