The single flagellum of African trypanosomes is essential in multiple aspects of the parasites' development. The FLAgellar Member 8 protein (FLAM8), localised to the tip of the flagellum in cultured insect forms of Trypanosoma brucei, was identified as a marker of the locking event that controls flagellum length. Here, we investigated whether FLAM8 could also reflect the flagellum maturation state in other parasite cycle stages.
View Article and Find Full Text PDFPrimary defects in motile cilia result in dysfunction of the apparatus responsible for generating fluid flows. Defects in these mechanisms underlie disorders characterized by poor mucus clearance, resulting in susceptibility to chronic recurrent respiratory infections, often associated with infertility; laterality defects occur in about 50% of such individuals. Here we report biallelic variants in LRRC56 (known as oda8 in Chlamydomonas) identified in three unrelated families.
View Article and Find Full Text PDFIntraflagellar transport (IFT) is the rapid bidirectional movement of large protein complexes driven by kinesin and dynein motors along microtubule doublets of cilia and flagella. In this study, we used a combination of high-resolution electron and light microscopy to investigate how and where these IFT trains move within the flagellum of the protist Focused ion beam scanning electron microscopy (FIB-SEM) analysis of trypanosomes showed that trains are found almost exclusively along two sets of doublets (3-4 and 7-8) and distribute in two categories according to their length. High-resolution live imaging of cells expressing mNeonGreen::IFT81 or GFP::IFT52 revealed for the first time IFT trafficking on two parallel lines within the flagellum.
View Article and Find Full Text PDFArtesunate, the recommended drug for severe malaria, rapidly clears the malaria parasite from infected patients but frequently induces anemia-called post-artesunate delayed hemolysis (PADH)-for which a simple predictive test is urgently needed. The underlying event in PADH is the expulsion of artesunate-exposed parasites from their host erythrocytes by pitting. We show that the histidine-rich protein 2 (HRP2) of the malaria parasite persists in the circulation of artesunate-treated malaria patients in Bangladesh and in French travelers who became infected with malaria in Africa.
View Article and Find Full Text PDFIntraflagellar transport (IFT) is required for construction of most cilia and flagella. Here, we used electron microscopy, immunofluorescence and live video microscopy to show that IFT is absent or arrested in the mature flagellum of Trypanosoma brucei upon RNA interference (RNAi)-mediated knockdown of IFT88 and IFT140, respectively. Flagella assembled prior to RNAi did not shorten, showing that IFT is not essential for the maintenance of flagella length.
View Article and Find Full Text PDFThe observation that the membranes of flagella are enriched in sterols and sphingolipids has led to the hypothesis that flagella might be enriched in raft-forming lipids. However, a detailed lipidomic analysis of flagellar membranes is not available. Novel protocols to detach and isolate intact flagella from Trypanosoma brucei procyclic forms in combination with reverse-phase liquid chromatography high-resolution tandem mass spectrometry allowed us to determine the phospholipid composition of flagellar membranes relative to whole cells.
View Article and Find Full Text PDFBackground: The three members of the ring-infected erythrocyte surface antigen (RESA) proteins family share high sequence homologies, which impair the detection and assignment to one or another protein of some pathogenic processes inherent to Plasmodium falciparum malaria. The present study was intended to determine if the antibody and inflammatory responses of children living in a malaria-endemic area varied depending on the RESA-1, RESA-2 or RESA-3 proteins and the severity of the disease, two groups of severe and uncomplicated malaria cases being considered.
Methods: Two synthetic peptides representing predicted B cell epitopes were designed per RESA protein, all located outside of the 3' and 5' repetition blocks, in order to allow an antibody detection specific of each member of the family.
The factors implicated in the transition from uncomplicated to severe clinical malaria such as pulmonary oedema and cerebral malaria remain unclear. It is known that alterations in vascular integrity due to endothelial cell (EC) activation and death occur during severe malaria. In this study, we assessed the ability of different P.
View Article and Find Full Text PDFProteins exported by Plasmodium falciparum to the red blood cell (RBC) membrane modify the structural properties of the parasitized RBC (Pf-RBC). Although quasi-static single cell assays show reduced ring-stage Pf-RBCs deformability, the parameters influencing their microcirculatory behavior remain unexplored. Here, we study the dynamic properties of ring-stage Pf-RBCs and the role of the parasite protein Pf155/Ring-Infected Erythrocyte Surface Antigen (RESA).
View Article and Find Full Text PDFBackground: Plasmodium falciparum exports proteins that remodel the erythrocyte membrane. One such protein, called Pf155/RESA (RESA1) contributes to parasite fitness, optimizing parasite survival during febrile episodes. Resa1 gene is a member of a small family comprising three highly related genes.
View Article and Find Full Text PDFThe virulence of the malaria parasite Plasmodium falciparum is mediated by parasite proteins exported to the surface of infected erythrocytes. In this issue, Maier et al. (2008) report a screen of malaria parasite genes predicted to be involved in parasite protein export and trafficking within the host erythrocyte and discover that many more than expected are essential for parasite survival in vitro.
View Article and Find Full Text PDFProtein phosphatase types 1 (PP1) and 2A (PP2A) represent two major families of serine/threonine protein phosphatases that have been implicated in the regulation of many cellular processes, including cell growth and apoptosis in mammalian cells. PP1 and PP2A proteins are composed of oligomeric complexes comprising a catalytic structure (PP1c or PP2AC) containing the enzymatic activity and at least one more interacting subunit. The binding of different subunits to a catalytic structure generates a broad variety of holoenzymes.
View Article and Find Full Text PDFDuring erythrocyte invasion, the Plasmodium falciparum Ring-infected erythrocyte surface antigen (RESA) establishes specific interactions with spectrin. Based on analysis of strains with a large chromosome 1 deletion, RESA has been assigned several functions, none of which is firmly established. Analysis of parasites with a disrupted resa1 gene and isogenic parental or resa3-disrupted controls confirmed the critical role of RESA in the surface reactivity of immune adult sera on glutaraldehyde-fixed ring stages.
View Article and Find Full Text PDFCDP-diacylglycerol synthase (CDS) is a key rate-limiting enzyme in the phospholipid metabolism of Plasmodium falciparum, converting phosphatidic acid to CDP-diacylglycerol. The CDS gene is predominantly expressed in the mature intraerythrocytic stages. Consequently, we physically and functionally characterized the CDS gene promoter.
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