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Targeting of the ring exported protein 1 to the Maurer's clefts is mediated by a two-phase process

Matthew W A Dixon1, Paula L Hawthorne, Tobias Spielmann

  • 1Malaria Biology Laboratory, Queensland Institute of Medical Research, Herston, QLD, Australia.

Traffic (Copenhagen, Denmark)
|May 21, 2008
PubMed

Insights

This study reveals how Plasmodium falciparum exports proteins without the Plasmodium export element (PEXEL). A specific region in REX1 protein facilitates its export as a soluble molecule.

Area of Science:

  • Malariology
  • Molecular Parasitology
  • Cell Biology

Background:

  • Plasmodium falciparum exports numerous proteins to the host erythrocyte during early development.
  • While many exported proteins utilize the Plasmodium export element (PEXEL) signal, some lack it.
  • The export mechanisms for PEXEL-negative proteins remain incompletely understood.

Purpose of the Study:

  • To investigate the export mechanism of the PEXEL-negative ring exported protein 1 (REX1).
  • To identify the specific sequence responsible for REX1 export.
  • To understand the localization and export state of REX1.

Main Methods:

  • Generation and analysis of transgenic parasites expressing green fluorescent protein-REX1 chimeras.
  • Biochemical characterization of REX1 chimeras.
  • Investigating the role of a coiled-coil motif in REX1 localization.

Main Results:

  • A single hydrophobic stretch plus 10 amino acids in REX1 mediate its export.
  • REX1 is exported as a soluble protein.
  • A coiled-coil motif is involved in the final localization of REX1 to Maurer's clefts.

Conclusions:

  • PEXEL-negative exported proteins can be secreted in a soluble form.
  • Sequences distinct from PEXEL motifs can mediate protein export across the parasitophorous vacuole membrane.
  • Maurer's clefts association is a late-stage event in REX1 export.

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