Trafficking of the exported P. falciparum chaperone PfHsp70x.
Plasmodium falciparum extensively modifies its chosen host cell, the mature human erythrocyte. This remodelling is carried out by parasite-encoded proteins that are exported into the host cell. To gain access to the human red blood cell, these proteins must cross the parasitophorous vacuole, a membrane bound compartment surrounding the parasite that is generated during the invasion process. Many exported proteins carry a so-called PEXEL/HT signal that directs their transport. We recently reported the unexpected finding of a species-restricted parasite-encoded Hsp70, termed PfHsp70x, which is exported into the host erythrocyte cytosol. PfHsp70x lacks a classical PEXEL/HT motif, and its transport appears to be mediated by a 7 amino acid motif directly following the hydrophobic N-terminal secretory signal. In this report, we analyse this short targeting sequence in detail. Surprisingly, both a reversed and scrambled version of the motif retained the capacity to confer protein export. Site directed mutagenesis of glutamate residues within this region leads to a block of protein trafficking within the lumen of the PV. In contrast to PEXEL-containing proteins, the targeting signal is not cleaved, but appears to be acetylated. Furthermore we show that, like other exported proteins, trafficking of PfHsp70x requires the vacuolar translocon, PTEX.
Parasitology, FB Biology, Philipps University Marburg, Karl von Frisch Strasse 8, 35043 Marburg, Germany.|Biochemistry Center (BZH), University of Heidelberg, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany.
Manuel
M
Rhiel
Parasitology, FB Biology, Philipps University Marburg, Karl von Frisch Strasse 8, 35043 Marburg, Germany.
Verena
V
Bittl
Parasitology, FB Biology, Philipps University Marburg, Karl von Frisch Strasse 8, 35043 Marburg, Germany.
Anke
A
Tribensky
Burnet Institute, Melbourne, Vic. 3004, Australia.|Monash University, Melbourne, Vic. 3800, Australia.
Sarah C
SC
Charnaud
Parasitology, FB Biology, Philipps University Marburg, Karl von Frisch Strasse 8, 35043 Marburg, Germany.
Maja
M
Strecker
Parasitology, FB Biology, Philipps University Marburg, Karl von Frisch Strasse 8, 35043 Marburg, Germany.
Sebastian
S
Müller
Zentrum für Infektiologie, Parasitologie, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany.
Michael
M
Lanzer
Zentrum für Infektiologie, Parasitologie, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany.
Cecilia
C
Sanchez
Laboratoire de Spectrométrie de Masse BioOrganique (LSMBO), IPHC, Université de Strasbourg, CNRS, UMR 7178, Strasbourg, France.
Christine
C
Schaeffer-Reiss
Laboratoire de Spectrométrie de Masse BioOrganique (LSMBO), IPHC, Université de Strasbourg, CNRS, UMR 7178, Strasbourg, France.
Benoit
B
Westermann
Burnet Institute, Melbourne, Vic. 3004, Australia.|Monash University, Melbourne, Vic. 3800, Australia.|University of Melbourne, Melbourne, Vic. 3010, Australia.
Brendan S
BS
Crabb
Burnet Institute, Melbourne, Vic. 3004, Australia.|Monash University, Melbourne, Vic. 3800, Australia.
Paul R
PR
Gilson
Parasitology, FB Biology, Philipps University Marburg, Karl von Frisch Strasse 8, 35043 Marburg, Germany.|Research School of Biology, ANU, Acton, ACT 2601, Australia.
Simone
S
Külzer
Parasitology, FB Biology, Philipps University Marburg, Karl von Frisch Strasse 8, 35043 Marburg, Germany.
Jude M
JM
Przyborski
D020816:Amino Acid Motifs; D004912:Erythrocytes / Q000378:metabolism / Q000469:parasitology; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D010963:Plasmodium falciparum / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport / Q000502:physiology; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*
D018840:HSP70 Heat-Shock Proteins; D015800:Protozoan Proteins