scholarly journals Loss of a doublecortin (DCX) domain containing protein causes structural defects in a tubulin-based organelle ofToxoplasma gondiiand impairs host cell invasion

2016 ◽  
Author(s):  
Eiji Nagayasu ◽  
Yu-chen Hwang ◽  
Jun Liu ◽  
John M. Murray ◽  
Ke Hu
Keyword(s):  
Host Cell ◽  
Cell Invasion ◽  
Polymer Structure ◽  
Structural Defects ◽  
Host Cell Invasion ◽  
Obligate Intracellular ◽  
Intracellular Parasites ◽  
Apical Complex ◽  
Cytoskeletal Elements ◽  
Special Arrangement

AbstractThe ~6000 species in phylum Apicomplexa are single-celled obligate intracellular parasites. Their defining characteristic is the “apical complex”, membranous and cytoskeletal elements at the apical end of the cell that participate in host-cell invasion. The apical complex ofToxoplasma gondiiand some other apicomplexans includes a cone-shaped assembly, the “conoid”, which (inT. gondii) comprises 14 spirally arranged fibers that are non-tubular polymers of tubulin. The tubulin dimers used for the conoid fibers make canonical microtubules elsewhere in the same cell, suggesting that their special arrangement in the conoid fibers is dictated by non-tubulin proteins. One candidate for this role is TgDCX, which has a doublecortin (DCX) domain and a TPPP/P25-alpha domain, known modulators of tubulin polymer structure. Loss of TgDCX radically disrupts the structure of the conoid, severely impairs host cell invasion, and slows growth. The defects of TgDCX-null parasites are corrected by re-introduction of a TgDCX coding sequence.

scholarly journals Loss of a doublecortin (DCX)-domain protein causes structural defects in a tubulin-based organelle of Toxoplasma gondii and impairs host-cell invasion

2017 ◽  
Vol 28 (3) ◽  
pp. 411-428 ◽  
Author(s):  
Eiji Nagayasu ◽  
Yu-Chen Hwang ◽  
Jun Liu ◽  
John M. Murray ◽  
Ke Hu
Keyword(s):  
Toxoplasma Gondii ◽  
Host Cell ◽  
Cell Invasion ◽  
Chemotherapeutic Agents ◽  
Structural Defects ◽  
Host Cell Invasion ◽  
Polymeric Form ◽  
Intracellular Parasites ◽  
Apical Complex ◽  
Cytoskeletal Elements

The ∼6000 species in phylum Apicomplexa are single-celled obligate intracellular parasites. Their defining characteristic is the apical complex—membranous and cytoskeletal elements at the apical end of the cell that participate in host-cell invasion. The apical complex of Toxoplasma gondii and some other apicomplexans includes a cone-shaped assembly, the conoid, which in T. gondii comprises 14 spirally arranged fibers that are nontubular polymers of tubulin. The tubulin dimers of the conoid fibers make canonical microtubules elsewhere in the same cell, suggesting that nontubulin protein dictates their special arrangement in the conoid fibers. One candidate for this role is TgDCX, which has a doublecortin (DCX) domain and a TPPP/P25-α domain, both of which are known modulators of tubulin polymer structure. Loss of TgDCX radically disrupts the structure of the conoid, severely impairs host-cell invasion, and slows growth. Both the conoid structural defects and the impaired invasion of TgDCX-null parasites are corrected by reintroduction of a TgDCX coding sequence. The nontubular polymeric form of tubulin found in the conoid is not found in the host cell, suggesting that TgDCX may be an attractive target for new parasite-specific chemotherapeutic agents.

Low Voltage Field Emission Scanning Electron Microscopy Provides Structural Evidence For Actin-Sized Filaments In Toxoplasma Gondii

1999 ◽  
Vol 5 (S2) ◽  
pp. 1130-1131
Author(s):  
Heide Schatten ◽  
David Sibley ◽  
Hans Ris
Keyword(s):  
Plasma Membrane ◽  
Toxoplasma Gondii ◽  
Host Cell ◽  
Field Emission ◽  
Cell Invasion ◽  
Low Voltage ◽  
Protozoan Parasite ◽  
Host Cell Invasion ◽  
Obligate Intracellular ◽  
Triton X

The protozoan parasite Toxoplasma gondiiis an obligate intracellular parasite that exhibits gliding and twisting motility during cell locomotion and host cell invasion. By using molecular and genetic approaches it has been determined that actin and myosin are localized beneath the parasite plasma membrane and produce the force for motility and active penetration during host cell invasion. However, structural evidence for actin fibers beneath the plasma membrane is still missing. Recently Chavez et al. demonstrated actin-like filaments in isolated cytoskeletal complexes. Our aproach has been to remove the cell membrane with 0.15% Triton X-100 in cytoskeleton preserving buffer, followed by imaging with low voltage field emission SEM. As seen in Fig. I, we could demonstrate the subpellicle actin network in parasites invading a host cell (arrow). Fig. 2 shows a similar subsurface network of actin filaments in a parasite gliding on glass.

scholarly journals Apicomplexan F-actin is required for efficient nuclear entry during host cell invasion

2019 ◽  
Author(s):  
Mario Del Rosario ◽  
Javier Periz ◽  
Georgios Pavlou ◽  
Oliver Lyth ◽  
Fernanda Latorre-Barragan ◽  
...  
Keyword(s):  
Host Cell ◽  
Cell Invasion ◽  
Traction Force ◽  
Super Resolution ◽  
Host Cells ◽  
Host Cell Invasion ◽  
Nuclear Entry ◽  
Apicomplexan Parasites ◽  
Intracellular Parasites ◽  
Pass Through

AbstractThe obligate intracellular parasites Toxoplasma gondii and Plasmodium spp. invade host cells by injecting a protein complex into the membrane of the targeted cell that bridges the two cells through the assembly of a ring-like junction. This circular junction stretches while the parasites applies a traction force to pass through; a step that typically concurs with transient constriction of the parasite body. Here we show that the junction can oppose resistance to the passage of the parasite’s nucleus. Super-resolution microscopy and real time imaging highlighted an F-actin pool at the apex of pre-invading parasite, an F-actin ring at the junction area during invasion but also networks of perinuclear and posteriorly localized F-actin. Mutant parasites with dysfunctional acto-myosin showed significant decrease of junctional and perinuclear F-actin and are coincidently affected in nuclear passage through the junction. We propose that the F-actin machinery eases nuclear passage by stabilising the junction and pushing the nucleus through the constriction, providing first evidence for a dual contribution of actin-forces during host cell invasion by apicomplexan parasites.

scholarly journals A Genome-Wide siRNA Screen Implicates Spire1/2 in SipA-Driven Salmonella Typhimurium Host Cell Invasion

PLoS ONE ◽  
2016 ◽  
Vol 11 (9) ◽  
pp. e0161965 ◽  
Author(s):  
Daniel Andritschke ◽  
Sabrina Dilling ◽  
Mario Emmenlauer ◽  
Tobias Welz ◽  
Fabian Schmich ◽  
...  
Keyword(s):  
Salmonella Typhimurium ◽  
Host Cell ◽  
Cell Invasion ◽  
Host Cell Invasion ◽  
Sirna Screen ◽  
Genome Wide ◽  
A Genome

Characterisation of NcGRA7 and NcSAG4 proteins: Immunolocalisation and their role in the host cell invasion by Neospora caninum tachyzoites

2010 ◽  
Vol 55 (4) ◽  
Author(s):  
Adriana Aguado-Martínez ◽  
Gema Álvarez-García ◽  
Gereon Schares ◽  
Verónica Risco-Castillo ◽  
Aurora Fernández-García ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Host Cell ◽  
Cell Invasion ◽  
Neospora Caninum ◽  
Parasitophorous Vacuole ◽  
Membrane Surface ◽  
Chronic Phase ◽  
Host Cell Invasion ◽  
Invasion Mechanisms ◽  
The Matrix

AbstractNeospora caninum negatively impacts bovine reproductive performance around the world. Addressing this problem requires a greater understanding of the parasite’s molecular biology. In this study, monoclonal antibodies against recombinant proteins were successfully developed and employed to characterise two different proteins of N. caninum: the acute phase-associated NcGRA7 and the chronic phase-associated NcSAG4. Immunofluorescence with the anti-rNcGRA7 monoclonal antibody suggested that NcGRA7 trafficks from tachyzoite dense granules to the matrix of the parasitophorous vacuole and parasite’s surroundings. Furthermore, NcGRA7 is also expressed in the bradyzoite stage and localised on the matrix of bradyzoite-positive vacuoles. NcGRA7 appears to be partially involved in the tachyzoite-invasion mechanisms, as an anti-rNcGRA7 monoclonal antibody partially inhibited in vitro tachyzoite-invasion. A monoclonal antibody specific for NcSAG4 confirmed this protein’s bradyzoitespecific expression both by western blot and immunofluorescence. However, some bradyzoite-positive vacuoles only weakly expressed NcSAG4, if it was expressed at all. The specificity of the anti-rNcSAG4 monoclonal antibody was confirmed by the recognition of the NcSAG4 in the membrane surface of Nc-1SAG4c transgenic tachyzoites, which constitutively expresses NcSAG4. Blocking NcSAG4 of Nc-1SAG4c tachyzoites with the monoclonal antibody did not affect host cell invasion. However, its implication on the host cell adhesion or host immune evasion should not be discarded.

scholarly journals 1,3,4-Thiadiazoles Effectively Inhibit Proliferation of Toxoplasma gondii

Cells ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1053
Author(s):  
Lidia Węglińska ◽  
Adrian Bekier ◽  
Katarzyna Dzitko ◽  
Barbara Pacholczyk-Sienicka ◽  
Łukasz Albrecht ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Host Cell ◽  
Cell Invasion ◽  
Direct Action ◽  
Human Fibroblasts ◽  
Imidazole Ring ◽  
Host Cells ◽  
In Vitro Assays ◽  
Host Cell Invasion

Congenital and acquired toxoplasmosis caused by the food- and water-born parasite Toxoplasma gondii (T. gondii) is one of the most prevalent zoonotic infection of global importance. T. gondii is an obligate intracellular parasite with limited capacity for extracellular survival, thus a successful, efficient and robust host cell invasion process is crucial for its survival, proliferation and transmission. In this study, we screened a series of novel 1,3,4-thiadiazole-2-halophenylamines functionalized at the C5 position with the imidazole ring (1b–12b) for their effects on T. gondii host cell invasion and proliferation. To achieve this goal, these compounds were initially subjected to in vitro assays to assess their cytotoxicity on human fibroblasts and then antiparasitic efficacy. Results showed that all of them compare favorably to control drugs sulfadiazine and trimethoprim in terms of T. gondii growth inhibition (IC50) and selectivity toward the parasite, expressed as selectivity index (SI). Subsequently, the most potent of them with meta-fluoro 2b, meta-chloro 5b, meta-bromo 8b, meta-iodo 11b and para-iodo 12b substitution were tested for their efficacy in inhibition of tachyzoites invasion and subsequent proliferation by direct action on established intracellular infection. All the compounds significantly inhibited the parasite invasion and intracellular proliferation via direct action on both tachyzoites and parasitophorous vacuoles formation. The most effective was para-iodo derivative 12b that caused reduction in the percentage of infected host cells by 44% and number of tachyzoites per vacuole by 93% compared to non-treated host cells. Collectively, these studies indicate that 1,3,4-thiadiazoles 1b–12b, especially 12b with IC50 of 4.70 µg/mL and SI of 20.89, could be considered as early hit compounds for future design and synthesis of anti-Toxoplasma agents that effectively and selectively block the invasion and subsequent proliferation of T. gondii into host cells.

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