Molecular characterisation of a novel family of cysteine-rich proteins of Toxoplasma gondii and ultrastructural evidence of oocyst wall localisation

Possenti, Alessia; Cherchi, Simona; Bertuccini, Lucia; Pozio, Edoardo; Dubey, J. P.; Spano, Furio

doi:10.1016/j.ijpara.2010.06.009

Cited by 58 publications

(92 citation statements)

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“…Infections lead to possible deleterious ocular and neurological complications and even death (7). In this context, a global effort has emerged to decipher the basic structures (8,9) and biological processes of the oocyst (10)(11)(12)(13) that allow the parasite to survive different environmental conditions and disinfectants (14)(15)(16)(17)(18).…”

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confidence: 99%

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Mechanics of the Toxoplasma gondii oocyst wall

Dumètre

Dubey

Ferguson

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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The ability of microorganisms to survive under extreme conditions is closely related to the physicochemical properties of their wall. In the ubiquitous protozoan parasite Toxoplasma gondii, the oocyst stage possesses a bilayered wall that protects the dormant but potentially infective parasites from harsh environmental conditions until their ingestion by the host. None of the common disinfectants are effective in killing the parasite because the oocyst wall acts as a primary barrier to physical and chemical attacks. Here, we address the structure and chemistry of the wall of the T. gondii oocyst by combining wall surface treatments, fluorescence imaging, EM, and measurements of its mechanical characteristics by using atomic force microscopy. Elasticity and indentation measurements indicated that the oocyst wall resembles common plastic materials, based on the Young moduli, E, evaluated by atomic force microscopy. Our study demonstrates that the inner layer is as robust as the bilayered wall itself. Besides wall mechanics, our results suggest important differences regarding the nonspecific adhesive properties of each layer. All together, these findings suggest a key biological role for the oocyst wall mechanics in maintaining the integrity of the T. gondii oocysts in the environment or after exposure to disinfectants, and therefore their potential infectivity to humans and animals.oocyst structure | oocyst integrity | oocyst resistance | Toxoplasma infectivity | transmission

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confidence: 99%

“…10, 12, and 22 and the present study). The oocyst wall is made of more than 90% proteins with several structural cysteineand tyrosine-rich proteins having been identified in the outer layer only (13) or in whole oocyst wall fractions (10,12). How these different proteins are processed and/or packed to form the oocyst wall is still not clear (8).…”

mentioning

confidence: 99%

Mechanics of the Toxoplasma gondii oocyst wall

Dumètre

Dubey

Ferguson

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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“…The cyst/ oocyst wall plays a key role by forming a highly resistant barrier to a large set of physicochemical stressors and by, at the same time, exhibiting surface properties involved in parasite-particle interactions (7,23,30,101). Though the biochemical composition and molecular architecture of their respective outer walls differ greatly (14,47,57,64,76,89,91) (Fig. 1), these three parasites could undergo similar surface interactions with their surrounding world due to their biophysical features (Table 1).…”

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confidence: 99%

Interaction Forces Drive the Environmental Transmission of Pathogenic Protozoa

Dumètre

Aubert

Puech

et al. 2012

Appl Environ Microbiol

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The protozoan parasites Giardia duodenalis, Cryptosporidium spp., and Toxoplasma gondii are pathogens that are resistant to a number of environmental factors and pose significant risks to public health worldwide. Their environmental transmission is closely governed by the physicochemical properties of their cysts (Giardia) and oocysts (Cryptosporidium and Toxoplasma), allowing their transport, retention, and survival for months in water, soil, vegetables, and mollusks, which are the main reservoirs for human infection. Importantly, the cyst/oocyst wall plays a key role in that regard by exhibiting a complex polymeric coverage that determines the charge and hydrophobic characteristics of parasites' surfaces. Interaction forces between parasites and other environmental particles may be, in a first approximation, evaluated following the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory of colloidal stability. However, due to the molecular topography and nano-to microstructure of the cyst/oocyst surface, non-DVLO hydrophobic forces together with additional steric attractive and/or repulsive forces may play a pivotal role in controlling the parasite behavior when the organism is subjected to various external conditions. Here, we review several parameters that enhance or hinder the adhesion of parasites to other particles and surfaces and address the role of fast-emerging techniques for mapping the cyst/oocyst surface, e.g., by measuring its topology and the generated interaction forces at the nano-to microscale. We discuss why characterizing these interactions could be a crucial step for managing the environmental matrices at risk of microbial pollution.

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“…Toxoplasma oocyst wall proteins include Cys-and His-rich OWPs similar to those of Cryptosporidium oocyst walls and Tyr-rich proteins similar to those of Eimeria oocyst walls (21,(40)(41)(42). A Cys-rich repeat protein which is also present in Eimeria oocyst walls binds to deproteinated oocyst walls, suggesting that it is either a lectin or a lipid-binding protein (our unpublished data).…”

Section: Fifth Strategy: Make Models For the Structure Of Cyst And Oomentioning

confidence: 79%

“…2H) (9,11). In contrast, there is likely little commonality between oocyst walls of Toxoplasma and tissue cyst walls, which do not look similar by TEM, do not have similar staining properties, and do not share many proteins (according to gene expression studies at ToxoDB) (15,16,33,(40)(41)(42). While fluorescence microscopy, expression studies, and knockouts have suggested a number of important properties of Toxoplasma tissue cysts (sugars bound by dolichos lectin, bradyzoite-specific antigens, and rhoptry proteins), there is presently no detailed model of the structure of tissue cyst walls, and no sugar polymers or acid-fast lipids have been identified (Fig.…”

Section: Fifth Strategy: Make Models For the Structure Of Cyst And Oomentioning

confidence: 99%

Strategies To Discover the Structural Components of Cyst and Oocyst Walls

et al. 2013

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bCysts of Giardia lamblia and Entamoeba histolytica and oocysts of Toxoplasma gondii and Cryptosporidium parvum are the infectious and sometimes diagnostic forms of these parasites. To discover the structural components of cyst and oocyst walls, we have developed strategies based upon a few simple assumptions. Briefly, the most abundant wall proteins are identified by monoclonal antibodies or mass spectrometry. Structural components include a sugar polysaccharide (chitin for Entamoeba, ␤-1,3-linked glucose for Toxoplasma, and ␤-1,3-linked GalNAc for Giardia) and/or acid-fast lipids (Toxoplasma and Cryptosporidium). Because Entamoeba cysts and Toxoplasma oocysts are difficult to obtain, studies of walls of nonhuman pathogens (E. invadens and Eimeria, respectively) accelerate discovery. Biochemical methods to dissect fungal walls work well for cyst and oocyst walls, although the results are often unexpected. For example, echinocandins, which inhibit glucan synthases and kill fungi, arrest the development of oocyst walls and block their release into the intestinal lumen. Candida walls are coated with mannans, while Entamoeba cysts are coated in a dextran-like glucose polymer. Models for cyst and oocyst walls derive from their structural components and organization within the wall. Cyst walls are composed of chitin fibrils and lectins that bind chitin (Entamoeba) or fibrils of the ␤-1,3-GalNAc polymer and lectins that bind the polymer (Giardia). Oocyst walls of Toxoplasma have two distinct layers that resemble those of fungi (␤-1,3-glucan in the inner layer) or mycobacteria (acid-fast lipids in the outer layer). Oocyst walls of Cryptosporidium have a rigid bilayer of acid-fast lipids and inner layer of oocyst wall proteins. Acid-fast lipids, Fibrils of beta-glucan, Dityrosine glows.-Anonymous, Haiku of the oocyst wall I n this minireview, we discuss strategies that have worked well to discover structural components of protist walls that allow them to travel by the fecal-oral route from one person to the next (1-5). Proteins and sugars are the major components of cyst walls of Entamoeba and Giardia, which cause amebic dysentery and diarrhea, respectively (6-8). In addition to proteins and carbohydrates, lipids are important structural components of oocyst walls of Cryptosporidium and Toxoplasma, which cause diarrhea and disseminated infections, respectively (9-11).To characterize the structural components of walls of so many different organisms, we have had to focus on what is likely to matter most. Many of these wall-oriented strategies are based upon a set of assumptions that may not be obvious to investigators working on stages of the parasites that are motile and dividing (12). Therefore, we review here the strategies and assumptions most useful to determine the protein, carbohydrate, and lipid compositions of cyst and oocyst walls. The compositions of these cyst and oocyst walls are then used to make simple, if incomplete, models for their structure and assembly.

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Molecular characterisation of a novel family of cysteine-rich proteins of Toxoplasma gondii and ultrastructural evidence of oocyst wall localisation

Cited by 58 publications

References 31 publications

Mechanics of the Toxoplasma gondii oocyst wall

Mechanics of the Toxoplasma gondii oocyst wall

Interaction Forces Drive the Environmental Transmission of Pathogenic Protozoa

Strategies To Discover the Structural Components of Cyst and Oocyst Walls

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