Plasmodium lipid rafts contain proteins implicated in vesicular trafficking and signalling as well as members of the PIR superfamily, potentially implicated in host immune system interactions

Abstract

Plasmodium parasites, the causal agents of malaria, dramatically modify the infected erythrocyte by exporting parasite proteins into one or multiple erythrocyte compartments, the cytoplasm and the plasma membrane or beyond. Despite advances in defining signals and specific cellular compartments implicated in protein trafficking in Plasmodium-infected erythrocytes, the contribution of lipid-mediated sorting to this cellular process has been poorly investigated. In this study, we examined the proteome of cholesterol-rich membrane microdomains or lipid rafts, purified from erythrocytes infected by the rodent parasite Plasmodium berghei. Besides structural proteins associated with invasive forms, we detected chaperones, proteins implicated in vesicular trafficking, membrane fusion events and signalling. Interestingly, the raft proteome of mixed P. berghei blood stages included proteins encoded by members of a large family (bir) of putative variant antigens potentially implicated in host immune system interactions and targeted to the surface of the host erythrocytes. The generation of transgenic parasites expressing BIR/GFP fusions confirmed the dynamic association of members of this protein family with membrane microdomains. Our results indicated that lipid rafts in Plasmodium-infected erythrocytes might constitute a route to sort and fold parasite proteins directed to various host cell compartments including the cell surface.

Biosynthesis of GDP-fucose and Other Sugar Nucleotides in the Blood Stages of Plasmodium falciparum

“…Non-infected red blood cells were lysed and included as controls in every analysis to discard noise due to the detection of sugar nucleotides carried away from the erythrocytes. The suspension was incubated on ice until lysis was completed (ϳ10 min) (29). Pellets were washed three times with cold phosphate-buffered saline (PBS), and sugar nucleotide analysis was performed as described elsewhere (30).…”

Proteomic Analysis of Detergent-resistant Membrane Microdomains in Trophozoite Blood Stage of the Human Malaria Parasite Plasmodium falciparum

“…Detected proteins only partially overlap with DRM components of the P. falciparum late schizonts (16,17) or the mixed blood stages of the rodent malaria agent P. berghei (18). Immunolocalization of selected DRM-associated proteins indicated that these assemblies may reside in both exported compartments (PVM, MCs) and intracellular membranes/organelles.…”

Proteome Analysis of Plasmodium falciparum Extracellular Secretory Antigens at Asexual Blood Stages Reveals a Cohort of Proteins with Possible Roles in Immune Modulation and Signaling

“…A number of studies have identified Plasmodium proteins that contain signature sequence motifs, the host cell targeting signal or the Plasmodium export element (PEXEL), that target these proteins into the infected erythrocytes (10,11). Recent proteomics analyses have identified novel proteins in the raftlike membranes of the parasite and on the surface of infected erythrocytes (12,13). P. falciparum translationally controlled tumor protein (PfTCTP), a homolog of the mammalian histamine-releasing factor, has been shown to be released into the culture supernatant from intact as well as ruptured infected RBCs and causes histamine release from human basophils and IL-8 secretion from eosinophils (14).…”