The polar ring of coccidian sporozoites: A unique microtubule-organizing centre

Russell, David G.; Burns, Robert

doi:10.1242/jcs.65.1.193

Cited by 96 publications

(19 citation statements)

References 26 publications

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“…T. gondii has 22 subpellicular microtubules each of which is about 5 μm in length . They are associated with the apical polar ring and a circular microtubule organizing center (MTOC) which is unique to the Apicomplexa. , There is an intimate association of these subpellicular microtubules with the inner membrane complex via the inner membrane particles which contain microtubule associated proteins . The conoid at the anterior end of the parasite consists of a novel polymer of tubulin attached to the preconoidal rings .…”

Section: Discussionmentioning

confidence: 99%

Post-Translational Modifications to Toxoplasma gondii α- and β-Tubulins Include Novel C-Terminal Methylation

et al. 2009

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Toxoplasma gondii is an apicomplexan of both medical and veterinary importance which is classified as an NIH Category B priority pathogen. It is best known for its ability to cause congenital infection in immune competent hosts and encephalitis in immune compromised hosts. The highly stable and specialized microtubule-based cytoskeleton participates in the invasion process. The genome encodes three isoforms of both α-and β-tubulin and we show that the tubulin is extensively altered by specific post-translational modifications (PTMs) in this paper. T. gondii tubulin PTMs were analyzed by mass spectrometry and immunolabeling using specific antibodies. The PTMs identified on α-tubulin included acetylation of Lys40, removal of the last C-terminal amino acid residue Tyr453 (detyrosinated tubulin) and truncation of the last five amino acid residues. Polyglutamylation was detected on both α-and β-tubulins. An antibody directed against mammalian α-tubulin lacking the last two C-terminal residues (Δ2-tubulin) labeled the apical region of this parasite. Detyrosinated tubulin was diffusely present in subpellicular microtubules and displayed an apparent accumulation at the basal end. Methylation, a PTM not previously described on tubulin, was also detected. Methylated tubulins were not detected in the host cells, human foreskin fibroblasts, suggesting that this may be a modification specific to the Apicomplexa.

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Section: Discussionmentioning

confidence: 99%

Post-Translational Modifications to Toxoplasma gondii α- and β-Tubulins Include Novel C-Terminal Methylation

et al. 2009

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“…Subpellicular microtubules radiate from the MTOC, known as the polar ring, and progressively surround the bound nucleus and the set of organelles attached to the nuclear membrane. As the microtubule skeleton is likely to grow inside the mother cell (fast‐growing ends of microtubules typically are distal to the MTOC, including in the Apicomplexan Eimeria ; Russell and Burns, 1984), a cell may be formed by progressively docking the plasma membrane around the internally growing skeleton. Alternatively, the inner membrane–microtubule lattice may be pushed out as it is formed, and daughter cells extruded from the mother cell surface.…”

Section: Discussionmentioning

confidence: 99%

Levels of circumsporozoite protein in the Plasmodium oocyst determine sporozoite morphology

et al. 2002

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The sporozoite stage of the Plasmodium parasite is formed by budding from a multinucleate oocyst in the mosquito midgut. During their life, sporozoites must infect the salivary glands of the mosquito vector and the liver of the mammalian host; both events depend on the major sporozoite surface protein, the circumsporozoite protein (CS). We previously reported that Plasmodium berghei oocysts in which the CS gene is inactivated do not form sporozoites. Here, we analyzed the ultrastructure of P.berghei oocyst differentiation in the wild type, recombinants that do not produce or produce reduced amounts of CS, and corresponding complemented clones. The results indicate that CS is essential for establishing polarity in the oocyst. The amounts of CS protein correlate with the extent of development of the inner membranes and associated microtubules underneath the oocyst outer membrane, which normally demarcate focal budding sites. This is a first example of a protein controlling both morphogenesis and infectivity of a parasite stage.

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“…In addition to the two secretory organelles, the apical complex is constituted by the conoid (a mesh of coiled microtubules limited at the top by the preconoidal rings and at the bottom by the inner polar ring) and two intraconoidal microtubules [79,90] (Figure 2A). The inner polar ring is a microtubule organizing center (MTOC) [91][92][93]. The conoid seems to be necessary for host cell invasion, although its function is not yet fully understood [88].…”

Section: Zoites Motile Stagesmentioning

confidence: 99%

The Apicomplexan Parasite Toxoplasma gondii

et al. 2022

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Toxoplasma gondii is a ubiquitous zoonotic parasite with an obligatory intracellular lifestyle. It relies on a specialized set of cytoskeletal and secretory organelles for host cell invasion. When infecting its felid definitive host, T. gondii undergoes sexual reproduction in the intestinal epithelium, producing oocysts that are excreted with the feces and sporulate in the environment. In other hosts and/or tissues, T. gondii multiplies by asexual reproduction. Rapidly dividing tachyzoites expand through multiple tissues, particularly nervous and muscular tissues, and eventually convert to slowly dividing bradyzoites which produce tissue cysts, structures that evade the immune system and remain infective within the host. Infection normally occurs through ingestion of sporulated oocysts or tissue cysts. While T. gondii is able to infect virtually all warm-blooded animals, most infections in humans are asymptomatic, with clinical disease occurring most often in immunocompromised hosts or fetuses carried by seronegative mothers that are infected during pregnancy.

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The polar ring of coccidian sporozoites: A unique microtubule-organizing centre

Cited by 96 publications

References 26 publications

Post-Translational Modifications to Toxoplasma gondii α- and β-Tubulins Include Novel C-Terminal Methylation

Post-Translational Modifications to Toxoplasma gondii α- and β-Tubulins Include Novel C-Terminal Methylation

Levels of circumsporozoite protein in the Plasmodium oocyst determine sporozoite morphology

The Apicomplexan Parasite Toxoplasma gondii

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