Characterization and function of the microsporidian polar tube

A review

Elaine M. Keohane, Louis M. Weiss

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

Microsporidia are eukaryotic, obligate intracellular organisms defined by their small spores containing a single polar tube that coils around the interior of the spore. After appropriate stimuli the germination of spores occurs. Conditions that promote germination vary widely among species, presumably reflecting the organism's adaptation to their host and external environment as well as preventing accidental discharge in the environment. It appears that calcium may be a key ion in this process. Regardless of the stimuli required for activation, all microsporidia exhibit the same response to the stimuli, that is, increasing the intrasporal osmotic pressure. This results in an influx of water into the spore accompanied by swelling of the polaroplasts and posterior vacuole. The polar tube then discharges from the anterior pole of the spore in an explosive reaction and is thought to form a hollow tube by a process of eversion. If the polar tube is discharged next to a cell, it can pierce the cell and transfer the sporoplasm into this cell. Polar tubes resist dissociation in detergents and acids but dissociate in dithiothreitol. We have developed a method for the purification of polar tube proteins (PTPs) using differential extraction followed by reverse phase high performance liquid chromatography (HPLC). This method was used to purify for subsequent characterization PTPs from Glugea americanus, Encephalitozoon cuniculi, E. hellem and E. intestinalis. These proteins appear to be members of a protein family that demonstrate conserved characteristics in solubility, hydrophobicity, mass, proline content and immunologic epitopes. These characteristics are probably important in the function of this protein in its self assembly during the eversion of the polar tube and in providing elasticity and resiliency for sporoplasm passage.

Original languageEnglish (US)
Pages (from-to)117-127
Number of pages11
JournalFolia Parasitologica
Volume45
Issue number2
StatePublished - 1998

Fingerprint

Microsporidia
Spores
spores
Germination
Proteins
proteins
Glugea
Encephalitozoon hellem
Encephalitozoon cuniculi
purification methods
dithiothreitol
reversed-phase liquid chromatography
Dithiothreitol
Osmotic Pressure
organisms
Elasticity
spore germination
cells
Reverse-Phase Chromatography
elasticity (mechanics)

Keywords

  • Encephalitozoon
  • Glugea
  • Invasion mechanism
  • Microsporidia
  • Polar tube proteins
  • Protein purification

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Parasitology

Cite this

Characterization and function of the microsporidian polar tube : A review. / Keohane, Elaine M.; Weiss, Louis M.

In: Folia Parasitologica, Vol. 45, No. 2, 1998, p. 117-127.

Research output: Contribution to journalArticle

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