Functional characterization of a novel Toxoplasma gondii glycosyltransferase: UDP-N-acetyl-d-galactosamine:polypeptide N-acetylgalactosaminyltransferase-T3☆
Section snippets
Host cells and Toxoplasma gondii
For the production of cysts in vitro, tachyzoites from the cyst-forming Prugniaud strain of T. gondii (ΔHXGPRT knock-out parasites, kindly provided by D. Soldati, Imperial College, London, UK) were grown in human foreskin fibroblast (HFF) monolayers for 11 days in minimal essential medium containing Earle’s salts without NaHCO3, buffered with 25 mM Hepes, pH 7.0 (Gibco), and maintained at 37 °C at 0.03% CO2, as previously described [14]. Tachyzoites of the Prugniaud strain were maintained in
Results
In this report, we demonstrate the enzymatic activity and expression pattern of T. gondii ppGalNAc-T3. This is the second characterized ppGalNAc-T of protozoan origin.
Discussion
We identified, cloned, and expressed a novel functional T. gondii ppGalNAc-T isoform, ppGalNAc-T3, that is expressed at the transcriptional level in both tachyzoites and bradyzoites. This glycosyltransferase belongs to the family of enzymes that initiate, and thereby regulate, the synthesis of O-glycans on mucin-type glycoproteins. In common with the other members of the ppGalNAc-T family, T. gondii ppGalNAc-T3 is a type II membrane protein consisting of a short cytoplasmic tail, a single
Acknowledgements
We appreciate the long-standing support, encouragement, and advice provided by Dr. Victor Ginsburg. His warmth, scientific insight, and humanity will always be an inspiration for us.
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2016, Microbes and InfectionCitation Excerpt :Early reports suggested that GPI anchors are the predominant form of carbohydrate modification of Toxoplasma proteins [18–21]. However, there is now ample evidence that Toxoplasma proteins can be modified by both N- and O-linked pathways [18,22–27]. Intracellular Toxoplasma proteins decorated with β-O-GlcNAc residues have also been identified [27,28].
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Note. The nucleotide sequences described in this paper were submitted to the GenBank/NCBI Data Bank with the following Accession Nos. Toxoplasma gondii ppGalNAc-T3, AY160970 and AY424894. Portions of this work were presented in abstract form at the Seventh International Congress of Toxoplasmosis, Tarrytown, New York, 2003.