Induced activation of the Toxoplasma gondii nucleoside triphosphate hydrolase leads to depletion of host cell ATP levels and rapid exit of intracellular parasites from infected cells

Jared A. Silverman, Huilin Qi, Angela Riehl, Con Beckers, Valerian Nakaar, Keith A Joiner

Research output: Contribution to journalArticle

65 Citations (Scopus)

Abstract

The nucleoside triphosphate hydrolase of Toxoplasma gondii is a potent apyrase. The protein is synthesized in large amounts and transported through the secretory pathway of the parasite and into the vacuolar space in an oxidized and thereby enzymatically inactive form. Complete activation of the purified enzyme is known to require dithiols (e.g. DTT); subcellular fractionation demonstrates that little if any (<5%) of the enzyme in the vacuolar space is active in the absence of DTT. Both native and epitope- tagged nucleoside triphosphate hydrolase (NTPase) were partially activated during immunoprecipitation, precluding precise assessment of enzyme activity in the vacuolar space but suggesting that protein-protein interactions may trigger activation. When infected cells were treated with DTT, the NTPase was activated in a dose-response fashion, as assessed by migration on SDS- polyacrylamide gel electrophoresis and by an increase in enzymatic activity. After activation, enzyme activity decreased with time in the presence of DTT; this inactivation was slowed by the presence of excess ATP. A rapid fall in host cell ATP was accompanied by an abrupt exit of parasites from cells. These results demonstrate that the oxidation/reduction status of the NTPase, the only parasite dense granule protein that contains disulfide bonds, is tightly controlled within the vacuolar space and may influence parasite exit from cells.

Original languageEnglish (US)
Pages (from-to)12352-12359
Number of pages8
JournalJournal of Biological Chemistry
Volume273
Issue number20
DOIs
StatePublished - May 15 1998
Externally publishedYes

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N-Glycosyl Hydrolases
Toxoplasma
Hydrolases
Nucleosides
Parasites
Adenosine Triphosphate
Chemical activation
Enzyme activity
Proteins
Enzymes
Apyrase
Enzyme Activation
Secretory Pathway
Fractionation
Electrophoresis
Immunoprecipitation
Disulfides
Oxidation-Reduction
Epitopes
Polyacrylamide Gel Electrophoresis

ASJC Scopus subject areas

  • Biochemistry

Cite this

Induced activation of the Toxoplasma gondii nucleoside triphosphate hydrolase leads to depletion of host cell ATP levels and rapid exit of intracellular parasites from infected cells. / Silverman, Jared A.; Qi, Huilin; Riehl, Angela; Beckers, Con; Nakaar, Valerian; Joiner, Keith A.

In: Journal of Biological Chemistry, Vol. 273, No. 20, 15.05.1998, p. 12352-12359.

Research output: Contribution to journalArticle

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