Trafficking of the exported P. falciparum chaperone PfHsp70x
Date
2016-11-08
Authors
Rhiel, Manuel
Bittl, Verena
Tribensky, Anke
Charnaud, Sarah C
Strecker, Maja
Müller, Sebastian
Lanzer, Michael
Sanchez, Cecilia
Schaeffer-Reiss, Christine
Westermann, Benoit
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Nature Publishing Group
Abstract
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.
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Keywords
amino acid motifs, erythrocytes, hsp70 heat-shock proteins, humans, Plasmodium falciparum, protein transport, protozoan proteins
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Scientific reports
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Journal article
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Open Access
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