The parasitophorous vacuole membrane surrounding intracellular Toxoplasma gondii functions as a molecular sieve

J. C. Schwab, C. J M Beckers, Keith A Joiner

Research output: Contribution to journalArticle

272 Citations (Scopus)

Abstract

The obligate intracellular protozoan parasite Toxoplasma gondii creates and enters into a unique membrane-bounded cytoplasmic compartment, the parasitophorous vacuole, when invading mammalian host cells. By microinjecting polar fluorescent molecules into individual T. gondii-infected fibroblasts, we show here that the parasitophorous vacuole membrane (PVM) surrounding the parasite functions as a molecular sieve. Lucifer yellow (457 Da) displayed free bidirectional flux across the PVM and distinctly outlined the parasites, which did not take up the dye, within the vacuole. This dye movement was not appreciably delayed by pretreatment of cells with 5 mM probenecid or chilling the monolayer to 5°C, suggesting that dye movement was due to passive permeation through a membrane pore rather than active transport. Calcein, fluo-3, and a series of fluorescein isothiocyanate- labeled peptides up to 1291 Da crossed the PVM in a size-restricted fashion. A labeled peptide of 1926 Da and labeled dextrans and proteins (≥3000 Da) failed to transit the PVM. This putative channel in the PVM therefore allows exchange of molecules up to 1300-1900 Da between the host cell cytoplasm and the parasitophorous vacuolar space.

Original languageEnglish (US)
Pages (from-to)509-513
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume91
Issue number2
StatePublished - Jan 18 1994
Externally publishedYes

Fingerprint

Intracellular Membranes
Toxoplasma
Vacuoles
Membranes
Parasites
Coloring Agents
Probenecid
Peptides
Active Biological Transport
Dextrans
Fluorescein
Cytoplasm
Fibroblasts
Cell Membrane

Keywords

  • apicomplexa
  • channel
  • fluorescence microscopy
  • microinjection
  • protozoa

ASJC Scopus subject areas

  • General
  • Genetics

Cite this

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AB - The obligate intracellular protozoan parasite Toxoplasma gondii creates and enters into a unique membrane-bounded cytoplasmic compartment, the parasitophorous vacuole, when invading mammalian host cells. By microinjecting polar fluorescent molecules into individual T. gondii-infected fibroblasts, we show here that the parasitophorous vacuole membrane (PVM) surrounding the parasite functions as a molecular sieve. Lucifer yellow (457 Da) displayed free bidirectional flux across the PVM and distinctly outlined the parasites, which did not take up the dye, within the vacuole. This dye movement was not appreciably delayed by pretreatment of cells with 5 mM probenecid or chilling the monolayer to 5°C, suggesting that dye movement was due to passive permeation through a membrane pore rather than active transport. Calcein, fluo-3, and a series of fluorescein isothiocyanate- labeled peptides up to 1291 Da crossed the PVM in a size-restricted fashion. A labeled peptide of 1926 Da and labeled dextrans and proteins (≥3000 Da) failed to transit the PVM. This putative channel in the PVM therefore allows exchange of molecules up to 1300-1900 Da between the host cell cytoplasm and the parasitophorous vacuolar space.

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