Linked Life Data

1328232

Source:http://linkedlifedata.com/resource/pubmed/id/1328232

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
30
pubmed:dateCreated
1992-11-25
pubmed:abstractText
Toxoplasmosis, a disease that affects humans and a wide variety of mammals is caused by Toxoplasma gondii, the obligate intracellular coccidian protozoan parasite. Most T. gondii research has focused on the rapidly growing invasive form, the tachyzoite, which expresses five major surface proteins attached to the parasite membrane by glycosylphosphatidylinositol (GPI) anchors. We have recently reported the purification and partial characterization of candidate precursor glycolipids (GPIs) from metabolically labeled parasites and have presented evidence that these GPIs have a linear glycan backbone sequence indistinguishable from the GPI core glycan of the major tachyzoite surface protein, P30. In this report, we describe a cell-free system derived from tachyzoite membranes which is capable of catalyzing GPI biosynthesis. Incubation of the membrane preparations with radioactive sugar nucleotides (GDP-[3H]mannose or UDP-[3H]GlcNAc) resulted in incorporation of radiolabeled into numerous glycolipids. By using a combination of chemical/enzymatic tests and chromatographic analysis, a series of incompletely glycosylated lipid species and mature GPIs have been identified. We have also established the involvement of Dol-P-mannose in the synthesis of T. gondii GPIs by demonstrating that the incorporation of [3H]mannose into the mannosylated GPIs is stimulated by dolichylphosphate and inhibited by amphomycin. In addition, increasing the concentration of nonradioactive GDP mannose resulted in a loss of radiolabel from the first easily detectable GPI precursor, GlcN-PI, and a concomittant appearance of the radio-activity into mannosylated glycolipids. Altogether, our data suggest that the GPI core glycan in T. gondii is assembled via sequential glycosylation of phosphatidylinositol, as proposed for the biosynthesis of GPIs in Trypanosoma brucei. In contrast to T. brucei, preliminary experiments indicate that the core glycan of some GPIs synthesized by the T. gondii cell-free system is modified by N-acetylgalactosamine similar to the situation for mammalian Thy-1.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
25
pubmed:volume
267
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
21446-58
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed-meshheading:1328232-Adenosine Triphosphate, pubmed-meshheading:1328232-Animals, pubmed-meshheading:1328232-Carbohydrate Sequence, pubmed-meshheading:1328232-Cell-Free System, pubmed-meshheading:1328232-Chromatography, Ion Exchange, pubmed-meshheading:1328232-Chromatography, Thin Layer, pubmed-meshheading:1328232-Coenzyme A, pubmed-meshheading:1328232-Dolichol Phosphates, pubmed-meshheading:1328232-Glycolipids, pubmed-meshheading:1328232-Glycosylphosphatidylinositols, pubmed-meshheading:1328232-Hydrolysis, pubmed-meshheading:1328232-Lipopeptides, pubmed-meshheading:1328232-Mannose, pubmed-meshheading:1328232-Molecular Sequence Data, pubmed-meshheading:1328232-Oligopeptides, pubmed-meshheading:1328232-Phosphatidylinositol Diacylglycerol-Lyase, pubmed-meshheading:1328232-Phosphoric Diester Hydrolases, pubmed-meshheading:1328232-Toxoplasma
pubmed:year
1992
pubmed:articleTitle
Biosynthesis of glycolipid precursors for glycosylphosphatidylinositol membrane anchors in a Toxoplasma gondii cell-free system.
pubmed:affiliation
Medizinische Zentrum für Hygiene and Medizinische Mikrobiologie, Philipps Universität Marburg, Germany.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't