Constitutive calcium-independent release of Toxoplasma gondii dense granules occurs through the NSF/SNAP/SNARE/Rab machinery

Sudha Chaturvedi, Huilin Qi, David Coleman, Anna Rodriguez, Phyllis I. Hanson, Boris Striepen, David S. Roos, Keith A Joiner

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50 Scopus citations


The signals and the molecular machinery mediating release of dense matrix granules from pathogenic protozoan parasites are unknown. We compared the secretion of the endogenous dense granule marker GRA3 in Toxoplasma gondii with the release of a stably transfected foreign reporter, β- lactamase, that localizes to parasite dense granules. Both proteins were released constitutively in a calcium-independent fashion, as shown using both intact and streptolysin O-permeabilized parasites. N-Ethylmaleimide and recombinant bovine Rab-guanine dissociation inhibitor inhibited β-lactamase secretion in permeabilized parasites, whereas recombinant hamster N- ethylmaleimide-sensitive fusion protein and bovine α-SNAP augmented release. Guanosine 5'-3-O-(thio)triphosphate, but not cAMP, augmented secretion in the presence but not in the absence of ATP. The T. gondii NSF/SNAP/SNARE/Rab machinery participates in dense granule release using parasite protein components that can interact functionally with their mammalian homolognes.

Original languageEnglish (US)
Pages (from-to)2424-2431
Number of pages8
JournalJournal of Biological Chemistry
Issue number4
Publication statusPublished - Jan 22 1999
Externally publishedYes


ASJC Scopus subject areas

  • Biochemistry

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