A parafusin-related Toxoplasma protein in Ca2+-regulated secretory organelles

Matthiesen, Steen H.; Shenoy, Shailesh M.; Kim, Kami; Singer, Robert H.; Satir, Birgit H.

doi:10.1078/0171-9335-00214

Cited by 33 publications

(40 citation statements)

References 46 publications

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“…Quantification of the co‐localized fluorescence stain suggested that only mature micronemes ready for exocytosis (about 24%) have PRP1. PRP1 appeared as the major labelled protein when tachyzoites were incubated with inorganic 32 P. We concluded that PRP1 was the PFUS orthologue of T. gondii (Matthiesen et al ., 2001).…”

Section: Introductionsupporting

confidence: 93%

“…PRP1 has been localized by immunofluorescence and deconvolution analysis to the micronemes in isolated tachyzoites (Matthiesen et al ., 2001). To examine the localization of PRP1 to the apical end of the parasite in greater structural detail, both ultra‐thin LR White‐ and cryo‐sections were produced.…”

Section: Resultsmentioning

confidence: 99%

“…The insert shows a panel of gold‐labelled micronemes from cryopreparations. Not all micronemes showed localization with PRP1, supporting previous data suggesting that only a fraction of mature organelles ready to release have PRP1 attached (Matthiesen et al ., 2001).…”

Section: Resultsmentioning

confidence: 99%

“…Previous studies demonstrated the presence of a protein called p arafusin r elated p rotein (PRP1) in T. gondii (Matthiesen et al . 2001).…”

Section: Introductionmentioning

confidence: 99%

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Role of the parafusin orthologue, PRP1, in microneme exocytosis and cell invasion inToxoplasma gondii

Matthiesen

Shenoy

Kim

et al. 2003

Cellular Microbiology

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SummaryThe association of PRP1, a Paramecium parafusin orthologue, with Toxoplasma gondii micronemes, now confirmed by immunoelectron microscopy, has here been studied in relation to exocytosis and cell invasion. PRP1 becomes labelled in vivo by inorganic 32 P and is dephosphorylated when ethanol is used to stimulate Ca 2+ + + + -dependent exocytosis of the micronemes. The ethanol Ca 2+ + + + -stimulated exocytosis is accompanied by translocation of PRP1 and microneme content protein (MIC3) from the apical end of the parasite. Immunoblotting showed that PRP1 is redistributed inside the parasite, while microneme content is secreted. To study whether similar changes occur during cell invasion, quantitative microscopy was performed during secretion, invasion and exit (egress) from the host cell. Time-course experiments showed that fluorescence intensities of PRP1 and MIC3 immediately after invasion were reduced 10-fold compared to preinvasion levels, indicating that PRP1 translocation and microneme secretion accompanies invasion. MIC3 regained fluorescence intensity and apical distribution after 15 min, while PRP1 recovered after 1 h. Intensity of both proteins then increased throughout the parasite division period until host cell lysis, suggesting the need to secrete microneme proteins to egress. These studies suggest that PRP1 associated with the secretory vesicle scaffold serves an important role in Ca 2+ + + + -regulated exocytosis and cell invasion.

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Section: Introductionsupporting

confidence: 93%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…Previous studies demonstrated the presence of a protein called p arafusin r elated p rotein (PRP1) in T. gondii (Matthiesen et al . 2001).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Role of the parafusin orthologue, PRP1, in microneme exocytosis and cell invasion inToxoplasma gondii

Matthiesen

Shenoy

Kim

et al. 2003

Cellular Microbiology

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“…Paralogs of the enzyme phosphoglucomutase (PGM) exist in various eukaryotes and function in calcium-mediated signaling events (Kim et al, 1992). This PGM paralog is called PFUS in Paramecium (Satir et al, 1989) and PRP1 in Toxoplasma (Matthiesen et al, 2001, 2003), with a putative ortholog also being present in the Plasmodium genome (Kats et al, 2008). RNA interference (RNAi) knock-down of PFUS in P. tetraurelia results in failed assembly of the DCSVs, which is consistent with a function in the secretory vesicle scaffold of DCSVs (Liu et al, 2011).…”

Section: Adaptations In Organelles and Functionmentioning

confidence: 99%

Evolution of apicomplexan secretory organelles

Gubbels

Duraisingh

2012

International Journal for Parasitology

103

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The alveolate superphylum includes many free-living and parasitic organisms, which are united by the presence of alveolar sacs lying proximal to the plasma membrane, providing cell structure. All species comprising the apicomplexan group of alveolates are parasites and have adapted to the unique requirements of the parasitic lifestyle. Here the evolution of apicomplexan secretory organelles that are involved in the critical process of egress from one cell and invasion of another is explored. The variations within the Apicomplexa and how these relate to species-specific biology will be discussed. In addition, recent studies have identified specific calcium-sensitive molecules that coordinate the various events and regulate the release of these secretory organelles within apicomplexan parasites. Some aspects of this machinery are conserved outside the Apicomplexa, and are beginning to elucidate the conserved nature of the machinery. Briefly, the relationship of this secretion machinery within the Apicomplexa will be discussed, compared with free-living and predatory alveolates, and how these might have evolved from a common ancestor.

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Secretion without membrane fusion: Porocytosis

Silver

Pappas

2005

The Anatomical Record Part B

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We have recently proposed a mechanism to describe secretion, a fundamental process in all cells. That hypothesis, called porocytosis, embodies all available data and encompasses both forms of secretion, i.e., vesicular and constitutive. The current accepted view of exocytotic secretion involves the physical fusion of vesicle and plasma membranes; however, that hypothesized mechanism does not fit all available physiological data. Energetics of apposed lipid bilayers do not favor unfacilitated fusion. We consider that calcium ions (e.g., 10(-4) to 10(-3) M calcium in microdomains when elevated for 1 ms or less), whose mobility is restricted in space and time, establish salt bridges among adjacent lipid molecules. This establishes transient pores that span both the vesicle and plasma membrane lipid bilayers; the diameter of this transient pore would be approximately 1 nm (the diameter of a single lipid molecule). The lifetime of the transient pore is completely dependent on the duration of sufficient calcium ion levels. This places the porocytosis hypothesis for secretion squarely in the realm of the physical and physical chemical interactions of calcium and phospholipids and places mass action as the driving force for release of secretory material. The porocytosis hypothesis that we propose satisfies all of the observations and provides a framework to integrate our combined knowledge of vesicular and constitutive secretion.

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A parafusin-related Toxoplasma protein in Ca2+-regulated secretory organelles

Cited by 33 publications

References 46 publications

Role of the parafusin orthologue, PRP1, in microneme exocytosis and cell invasion inToxoplasma gondii

Role of the parafusin orthologue, PRP1, in microneme exocytosis and cell invasion inToxoplasma gondii

Evolution of apicomplexan secretory organelles

Secretion without membrane fusion: Porocytosis

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