Plasmodium falciparum Pf34, a novel GPI-anchored rhoptry protein found in detergent-resistant microdomains

Proellocks, Nicholas Ian; Kovacevic, Svetozar; Ferguson, David J. P.; Kats, Lev; Morahan, Belinda Joan; Black, Casilda Gabrielle; Waller, Karena Louise; Coppel, Ross L.

doi:10.1016/j.ijpara.2007.03.013

Cited by 35 publications

(33 citation statements)

References 36 publications

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“…The existence of raft-like domains with distinct properties has been previously proposed for late endosomes, which contain cholesterol-rich microdomains both in their limiting membrane and in intraluminal vesicles (51). It was also shown that the fractionation patterns for two falciparum detergent-resistant rhoptry proteins differ, suggesting that multiple DRM populations exist within this organelle (52).…”

Section: Drm Rafts In Malaria Parasite Infection and Pathogenesis-mentioning

confidence: 66%

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

Yam

Birago

Fratini

et al. 2013

Molecular & Cellular Proteomics

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Intracellular pathogens contribute to a significant proportion of infectious diseases worldwide. The successful strategy of evading the immune system by hiding inside host cells is common to all the microorganism classes, which exploit membrane microdomains, enriched in cholesterol and sphingolipids, to invade and colonize the host cell. These assemblies, with distinct biochemical properties, can be isolated by means of flotation in sucrose density gradient centrifugation because they are insoluble in nonionic detergents at low temperature. We analyzed the protein and lipid contents of detergent-resistant membranes from erythrocytes infected by Plasmodium falciparum, the most deadly human malaria parasite. Proteins associated with membrane microdomains of trophic parasite blood stages (trophozoites) include an abundance of chaperones, molecules involved in vesicular trafficking, and enzymes implicated in host hemoglobin degradation. About 60% of the identified proteins contain a predicted localization signal suggesting a role of membrane microdomains in protein sorting/trafficking. To validate our proteomic data, we raised antibodies against six Plasmodium proteins not characterized previously. All the selected candidates were recovered in floating low-density fractions after density gradient centrifugation. The analyzed proteins localized either to internal organelles, such as the mitochondrion and the endoplasmic reticulum, or to exported membrane structures, the parasitophorous vacuole membrane and Maurer's clefts, implicated in targeting parasite proteins to the host erythrocyte cytosol or surface. The relative abundance of cholesterol and phospholipid species varies in gradient fractions containing detergent-resistant membranes, suggesting heterogeneity in the lipid composition of the isolated microdomain population. This study is the first report showing the presence of cholesterol-rich microdomains with distinct properties and subcellular localization in trophic stages of Plasmodium falciparum. Molecular

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Section: Drm Rafts In Malaria Parasite Infection and Pathogenesis-mentioning

confidence: 66%

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

Yam

Birago

Fratini

et al. 2013

Molecular & Cellular Proteomics

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“…To determine whether PfRON6 was localised within rhoptries or micronemes, double labelling experiments with anti-RAMA (a rhoptry marker), anti-Pf34 and anti-PfRON4 (rhoptry neck markers), and anti-AMA1 (a microneme marker) antibodies were performed (Fig. 4C) (Bannister et al, 2003; Topolska et al, 2004; Alexander et al, 2006; Proellocks et al, 2007). We analysed 10 images for each antibody pair and quantified co-localisation using Pearson’s coefficient (Supplementary Fig.…”

Section: Resultsmentioning

confidence: 99%

Characterisation of PfRON6, a Plasmodium falciparum rhoptry neck protein with a novel cysteine-rich domain

Proellocks

Kats

Sheffield

et al. 2009

International Journal for Parasitology

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The pathological consequences of malaria infection are the result of parasite replication within red blood cells (RBCs). Invasion into RBCs is mediated by a large repertoire of parasite proteins that are distributed on the parasite surface and within specialised apical secretory organelles. As invasion is an essential step in the parasite life-cycle, targeting invasion-related molecules provides an avenue for therapeutic intervention. We have used genome and transcriptome data available for Plasmodium falciparum to identify proteins likely to be involved in RBC invasion. Of these candidates, we selected a protein which we have dubbed PfRON6 for detailed characterisation. PfRON6 contains a novel cysteine-rich domain that is conserved in other Apicomplexan parasites. We show that PfRON6 is localised in the rhoptry neck of merozoites and is transferred to the newly formed parasitophorous vacuole during invasion. Transfection experiments indicate that the gene which encodes PfRON6 is refractory to integration that disrupts the coding sequence, suggesting its absence is incompatible with the parasite life-cycle. Further, the cysteine-rich domain appears to be functionally important as it cannot be truncated. Taken together, these data identify PfRON6 as a novel and potentially important component of the Plasmodium invasion machinery.

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“…Exceptions to this include rhoptry-associated membrane antigen (55), Pf34 (43), and apical sushi protein (19,41). Interestingly, the GPI-anchored proteins Pf38 (45) and MSP10 (4) have been suggested to have both surface and apical distributions.…”

Section: Discussionmentioning

confidence: 99%

Novel Putative Glycosylphosphatidylinositol-Anchored Micronemal Antigen of Plasmodium falciparum That Binds to Erythrocytes

Hinds¹,

Green²,

Knuepfer³

et al. 2009

Eukaryot Cell

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We have identified a new Plasmodium falciparum erythrocyte binding protein that appears to be located in the micronemes of the merozoite stage of the parasite and membrane linked through a glycosylphosphatidylinositol (GPI) anchor. The protein is designated GPI-anchored micronemal antigen (GAMA) and was identified by applying a set of selection criteria to identify previously uncharacterized merozoite proteins that may have a role in cell invasion. The protein is also present in the proteomes of the sporozoite and ookinete micronemes and is conserved throughout the genus. GAMA contains a novel domain that may be constrained by disulfide bonds and a predicted C-terminal hydrophobic sequence that is presumably replaced by the GPI. The protein is synthesized late during schizogony, processed into two fragments that are linked by a disulfide bond, and translocated to an apical location, which is probably the micronemes. In a proportion of free merozoites GAMA can also be detected on the parasite surface. Following erythrocyte invasion the bulk of the protein is shed in a soluble form, although a short C-terminal fragment may be carried into the newly invaded red blood cell. The protein was shown to bind reversibly to erythrocytes and therefore represents a new example of a host cell binding protein.Malaria is a potentially fatal disease that still devastates poverty-stricken nations more than a century after the protozoan parasite Plasmodium was identified as its causative agent. An accurate estimation of mortality remains elusive, although recent estimates suggest that just over 2.5 billion people live at risk of infection by Plasmodium falciparum (22), the species of the parasite responsible for the vast majority of deaths. It is believed that there are in the range of 500 million clinical episodes of P. falciparum infection each year, with the vast majority of the estimated 1 million fatalities occurring in children under the age of 5 years in sub-Saharan Africa (50). The often-fruitless efforts to develop a licensed malaria vaccine, along with the emergence of drug-resistant parasites and insecticide-resistant mosquitoes, highlight the urgency with which new points of attack to combat malaria need to be identified. The arrival of the P. falciparum genome sequence (15), along with its transcription (8, 34) and proteomic (14, 33) profiles, has provided great opportunities to identify novel drug and vaccine candidates.The asexual blood stage of the parasite is exclusively responsible for the clinical symptoms of malaria, and so, understandably, great efforts have gone into elucidating the molecular mechanism of erythrocyte invasion that is driven by the parasite's actomyosin motor. Although this process remains largely undefined, it is known that the secretory organelles located at the apical end of the invasive merozoite are pivotal. These organelles consist minimally of micronemes, rhoptries, and dense granules. Proteins belonging to the Duffy binding-like erythrocyte binding protein (18,37,49) and P. falciparum ...

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Plasmodium falciparum Pf34, a novel GPI-anchored rhoptry protein found in detergent-resistant microdomains

Cited by 35 publications

References 36 publications

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

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

Characterisation of PfRON6, a Plasmodium falciparum rhoptry neck protein with a novel cysteine-rich domain

Novel Putative Glycosylphosphatidylinositol-Anchored Micronemal Antigen of Plasmodium falciparum That Binds to Erythrocytes

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