Protein Sorting in Plasmodium Falciparum

Daniel Mayer

doi:10.3390/life11090937

Abstract

Plasmodium falciparum is a unicellular eukaryote with a very polarized secretory system composed of micronemes rhoptries and dense granules that are required for host cell invasion. P. falciparum, like its relative T. gondii, uses the endolysosomal system to produce the secretory organelles and to ingest host cell proteins. The parasite also has an apicoplast, a secondary endosymbiotic organelle, which depends on vesicular trafficking for appropriate incorporation of nuclear-encoded proteins into the apicoplast. Recently, the central molecules responsible for sorting and trafficking in P. falciparum and T. gondii have been characterized. From these studies, it is now evident that P. falciparum has repurposed the molecules of the endosomal system to the secretory pathway. Additionally, the sorting and vesicular trafficking mechanism seem to be conserved among apicomplexans. This review described the most recent findings on the molecular mechanisms of protein sorting and vesicular trafficking in P. falciparum and revealed that P. falciparum has an amazing secretory machinery that has been cleverly modified to its intracellular lifestyle.

Highlights

Plasmodium falciparum is a protozoan parasite that is responsible for millions of infections resulting in malaria, a devastating disease currently prevalent in sub-Saharan Africa.Malaria continues to be endemic in 87 countries with approximately 229 million cases and 2–3 million deaths [1]
This review described the most recent findings on the molecular mechanisms of protein sorting and vesicular trafficking in P. falciparum and revealed that P. falciparum has an amazing secretory machinery that has been cleverly modified to its intracellular lifestyle
It has recently been shown that Vps45, in both P. falciparum and T. gondii, is responsible for shipping both the endosomal and secretory vesicles

Summary

Introduction

Plasmodium falciparum is a protozoan parasite that is responsible for millions of infections resulting in malaria, a devastating disease currently prevalent in sub-Saharan Africa. P. falciparum has the unique challenge of residing and developing within a cell devoid of organelles. All the symptoms associated with malaria are due to the invasion, intracellular development, and egress of P. falciparum merozoites into the host’s erythrocytes [3]. Proteins are directed to the lumen of specific organelles, diverse intracellular membranes, the plasma membrane, or outside of the cell by the process of secretion [6]. In addition to trafficking proteins within its cell, the parasite ships proteins beyond its plasma membrane, into both the parasitophorous vacuole and into the host erythrocyte cytoplasm and plasma membrane [9,10]. In P. faclciparum, additional organelles named mononemes and exonemes have been described [12] The latter seems to play a role in the parasite egress [12]

Protein Sorting to ER and Golgi

Protein Sorting to the Apicoplast

Schematic

Protein Sorting to Food Vacuole

Conclusions