Toxoplasma gondii:A Family of Apical Antigens Associated with the Cytoskeleton

Morrissette, Naomi S.; Roos, David S.

doi:10.1006/expr.1998.4277

Cited by 14 publications

(12 citation statements)

References 21 publications

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“…Furthermore, a sharp transition between two distinct patterns of intramembrane particles on the IMC plates occurs at approximately the same position on the parasite as the location of the TgCentrin2 annuli and lower edge of the dynein cap, suggesting some functional connection. This cap region was previously shown to harbor a set of apically localized proteins defined by a panel of monoclonal antibodies [32,56]. …”

Section: Discussionmentioning

confidence: 99%

Cytoskeletal Components of an Invasion Machine—The Apical Complex of Toxoplasma gondii

et al. 2006

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The apical complex of Toxoplasma gondii is widely believed to serve essential functions in both invasion of its host cells (including human cells), and in replication of the parasite. The understanding of apical complex function, the basis for its novel structure, and the mechanism for its motility are greatly impeded by lack of knowledge of its molecular composition. We have partially purified the conoid/apical complex, identified ~200 proteins that represent 70% of its cytoskeletal protein components, characterized seven novel proteins, and determined the sequence of recruitment of five of these proteins into the cytoskeleton during cell division. Our results provide new markers for the different subcompartments within the apical complex, and revealed previously unknown cellular compartments, which facilitate our understanding of how the invasion machinery is built. Surprisingly, the extreme apical and extreme basal structures of this highly polarized cell originate in the same location and at the same time very early during parasite replication.

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Section: Discussionmentioning

confidence: 99%

Cytoskeletal Components of an Invasion Machine—The Apical Complex of Toxoplasma gondii

et al. 2006

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“…This MAP may coordinate the close interaction of the subpellicular microtubules with the IMC. The existence of a group of monoclonal antibodies that labels the subpellicular microtubules in Toxoplasma and crossreacts with Plasmodium suggests that the MAPs may be conserved within the Apicomplexa (112,114). The Plasmodium and Cryptosporidium genome databases and the Toxoplasma, Eimeria, and Neospora expressed sequence tag (EST) projects have sequences annotated as encoding putative kinesins and dyneins.…”

Section: Tubulin and Microtubule-associated Proteinsmentioning

confidence: 99%

Cytoskeleton of Apicomplexan Parasites

Morrissette

Sibley

2002

Microbiol Mol Biol Rev

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410

402

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The Apicomplexa are a phylum of diverse obligate intracellular parasites including Plasmodium spp., the cause of malaria; Toxoplasma gondii and Cryptosporidium parvum, opportunistic pathogens of immunocompromised individuals; and Eimeria spp. and Theileria spp., parasites of considerable agricultural importance. These protozoan parasites share distinctive morphological features, cytoskeletal organization, and modes of replication, motility, and invasion. This review summarizes our current understanding of the cytoskeletal elements, the properties of cytoskeletal proteins, and the role of the cytoskeleton in polarity, motility, invasion, and replication. We discuss the unusual properties of actin and myosin in the Apicomplexa, the highly stereotyped microtubule populations in apicomplexans, and a network of recently discovered novel intermediate filament-like elements in these parasites

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“…Few reports have been published on microtubule-associated proteins in apicomplexan parasites (Morrissette and Roos, 1998;Sasai et al, 1998), and it is not known to what extent these are related to microtuble associated proteins in other protozoa (Balaban and Goldmann, 1992;Hemphill et al, 1992;Rindisbacher et al, 1993;Detmer et al, 1997;Kohl and Gull, 1998). No microtubule-associated proteins have been characterized in N. caninum to date.…”

Section: Discussionmentioning

confidence: 94%

Monoclonal Antibody Directed Against Neospora Caninum Tachyzoite Carbohydrate Epitope Reacts Specifically With Apical Complex–associated Sialylated Beta Tubulin

Srinivasan¹,

Baszler

Vonlaufen

et al. 2006

Journal of Parasitology

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Monoclonal antibodies (mabs) were generated against whole sonicated Neospora caninum tachyzoites as immunogen. Initial ELISA screening of the reactivity of hybridoma culture supernatants using the same antigen and antigen treated with sodium periodate prior to antibody binding resulted in the identification of 8 supernatants with reactivity against putative carbohydrate epitopes. Following immunoblotting, mab6D12 (IgG1), binding a 52/48-kDa doublet, and mab6C6 (IgM), binding a 190/180-kDa doublet, were selected for further studies. Immunofluorescence of tachyzoite-infected cultures localized the corresponding epitopes not to the surface, but to interior epitopes at the apical part of N. caninum tachyzoites. During in vitro tachyzoite to bradyzoite stage conversion, mab6C6 labeling translocated toward the cyst periphery, while for mab6D12 no changes in localization were noted. Upon extraction of tachyzoites with the nonionic detergent Triton-X-100, the 52-kDa band recognized by mab6D12 was present exclusively in the insoluble, cytoskeletal fraction of both N. caninum and Toxoplasma gondii tachyzoites. Tandem mass spectrometry analysis identified this protein as N. caninum beta tubulin. The 48-kDa band labeled by mab6D12 was a Vero cell protein contamination. The protein(s) reacting with mab6C6 could not be conclusively identified by mass spectrometry. Immunofluorescence consistently failed to label T. gondii tachyzoites, indicating that beta tubulin in T. gondii and N. caninum could be differentially modified or that the reactive epitope in T. gondii is masked. Immunogold TEM of isolated apical cytoskeletal preparations and dual immunofluorescence with antibody to tubulin confirmed that mab6D12 binds to the anterior part of apical complex-associated microtubules. The sodium periodate sensitivity of the beta tubulin associated epitope was confirmed by immunoblotting and ELISA, and treatment of N. caninum cytoskeletal proteins with sialidase prior to mab6D12 labeling resulted in a profound loss of antibody binding, suggesting that mab6D12 reacts with sialylated beta tubulin.

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Toxoplasma gondii:A Family of Apical Antigens Associated with the Cytoskeleton

Cited by 14 publications

References 21 publications

Cytoskeletal Components of an Invasion Machine—The Apical Complex of Toxoplasma gondii

Cytoskeletal Components of an Invasion Machine—The Apical Complex of Toxoplasma gondii

Cytoskeleton of Apicomplexan Parasites

Monoclonal Antibody Directed Against Neospora Caninum Tachyzoite Carbohydrate Epitope Reacts Specifically With Apical Complex–associated Sialylated Beta Tubulin

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