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Uncovering common principles in protein export of malaria parasites

Christof Grüring1, Arlett Heiber, Florian Kruse

  • 1Bernhard Nocht Institute for Tropical Medicine, Parasitology Section, 20359 Hamburg, Germany.

Cell Host & Microbe
|November 20, 2012
PubMed

Insights

Malaria parasite Plasmodium falciparum protein export relies on a secondary N-terminal control mechanism beyond the PEXEL motif. This finding reveals shared export pathways for different parasite proteins, impacting malaria research.

Area of Science:

  • Cellular Biology
  • Parasitology
  • Molecular Biology

Background:

  • The malaria parasite Plasmodium falciparum extensively modifies host cells for proliferation.
  • Protein export into host cells is crucial, often mediated by proteins with a Plasmodium export element (PEXEL).
  • PEXEL cleavage and phosphatidylinositol-3-phosphate binding are considered key for protein export.

Purpose of the Study:

  • To investigate alternative protein export mechanisms in Plasmodium falciparum.
  • To identify novel control mechanisms governing parasite protein translocation.
  • To understand shared export properties among different classes of exported parasite proteins.

Main Methods:

  • Experimental manipulation to bypass PEXEL-mediated export requirements.
  • Analysis of N-terminal protein regions following PEXEL cleavage.
  • Comparative study of PEXEL-containing proteins and PEXEL-negative export proteins (PNEPs).
  • Investigation of protein unfolding and translocation dynamics.

Main Results:

  • PEXEL cleavage requirements for export can be bypassed.
  • A secondary export control mechanism resides in the N terminus generated post-cleavage.
  • This N-terminal region dictates export and is shared with PEXEL-negative export proteins (PNEPs).
  • Protein unfolding is essential for the export of both PEXEL and PNEP proteins, indicating translocation as a common step.
  • Translocation of transmembrane proteins precedes that of soluble proteins at the parasite periphery.

Conclusions:

  • Plasmodium falciparum protein export involves a sophisticated, multi-layered control system.
  • A conserved N-terminal export domain and unfolding-dependent translocation are common to diverse exported parasite proteins.
  • Complex, sequential translocation events occur at the parasite plasma membrane, refining our understanding of host cell modification by malaria parasites.

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