Experimental determination of the membrane topology of the Plasmodium protease Plasmepsin V

PLoS One. 2015 Apr 7;10(4):e0121786. doi: 10.1371/journal.pone.0121786. eCollection 2015.


The malaria parasite exports hundreds of proteins into its host cell. The majority of exported proteins contain a Host-Targeting motif (also known as a Plasmodium export element) that directs them for export. Prior to export, the Host-Targeting motif is cleaved by the endoplasmic reticulum-resident protease Plasmepsin V and the newly generated N-terminus is N-α-acetylated by an unidentified enzyme. The cleaved, N-α-acetylated protein is trafficked to the parasitophorous vacuole, where it is translocated across the vacuole membrane. It is clear that cleavage and N-α-acetylation of the Host-Targeting motif occur at the endoplasmic reticulum, and it has been proposed that Host-Targeting motif cleavage and N-α-acetylation occur either on the luminal or cytosolic side of the endoplasmic reticulum membrane. Here, we use self-associating 'split' fragments of GFP to determine the topology of Plasmepsin V in the endoplasmic reticulum membrane; we show that the catalytic protease domain of Plasmepsin V faces the endoplasmic reticulum lumen. These data support a model in which the Host-Targeting motif is cleaved and N-α-acetylated in the endoplasmic reticulum lumen. Furthermore, these findings suggest that cytosolic N-α-acetyltransferases are unlikely to be candidates for the N-α-acetyltransferase of Host-Targeting motif-containing exported proteins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylation
  • Amino Acid Motifs
  • Aspartic Acid Endopeptidases / genetics
  • Aspartic Acid Endopeptidases / metabolism*
  • Endoplasmic Reticulum / enzymology*
  • Endoplasmic Reticulum / genetics
  • Intracellular Membranes / enzymology*
  • Plasmodium falciparum / enzymology*
  • Plasmodium falciparum / genetics
  • Protein Transport / physiology
  • Protozoan Proteins / genetics
  • Protozoan Proteins / metabolism*
  • Vacuoles / enzymology*
  • Vacuoles / genetics


  • Protozoan Proteins
  • Aspartic Acid Endopeptidases
  • plasmepsin