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ABSTRACT: Plasmodium falciparum is predicted to transport over 300 proteins to the cytosol of its chosen host cell, the mature human erythrocyte, including 19 members of the Hsp40 family. Here, we have generated transfectant lines expressing GFP- or HA-Strep-tagged versions of these proteins, and used these to investigate both localization and other properties of these Hsp40 co-chaperones. These fusion proteins labelled punctate structures within the infected erythrocyte, initially suggestive of a Maurer's clefts localization. Further experiments demonstrated that these structures were distinct from the Maurer's clefts in protein composition. Transmission electron microscopy verifies a non-cleft localization for HA-Strep-tagged versions of these proteins. We were not able to label these structures with BODIPY-ceramide, suggesting a lower size and/or different lipid composition compared with the Maurer's clefts. Solubility studies revealed that the Hsp40-GFP fusion proteins appear to be tightly associated with membranes, but could be released from the bilayer under conditions affecting membrane cholesterol content or organization, suggesting interaction with a binding partner localized to cholesterol-rich domains. These novel structures are highly mobile in the infected erythrocyte, but based on velocity calculations, can be distinguished from the 'highly mobile vesicles' previously described. Our study identifies a further extra-parasitic structure in the P. falciparum-infected erythrocyte, which we name 'J-dots' (as their defining characteristic so far is the content of J-proteins). We suggest that these J-dots are involved in trafficking of parasite-encoded proteins through the cytosol of the infected erythrocyte.
Cellular Microbiology 10/2010; 12(10):1398-420. · 5.46 Impact Factor
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Trends in Parasitology 11/2008; 24(12):531. · 5.14 Impact Factor
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ABSTRACT: The malaria parasite undergoes a remarkable series of morphological transformations, which underpin its life in both human and mosquito hosts. The advent of molecular transfection technology coupled with the ability to introduce fluorescent reporter proteins that faithfully track and expose the activities of parasite proteins has revolutionized our view of parasite cell biology. The greatest insights have been realized in the erythrocyte stages of Plasmodium falciparum. P. falciparum invades and remodels the human erythrocyte: it feeds on haemoglobin, grows and divides, and subverts the physiology of its hapless host. Fluorescent proteins have been employed to track and dissect each of these processes and have revealed details and exposed new paradigms.
Trends in Parasitology 07/2007; 23(6):268-77. · 5.14 Impact Factor
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ABSTRACT: The wide availability of the confocal microscope and the emergence of green fluorescent protein (GFP) transfection technology has led to the increasing use of photobleaching studies to examine aspects of cellular dynamics in living cells. In this review, we examine the theory and practice of performing photobleaching studies using a confocal microscope. We illustrate the application of photobleaching protocols using our own measurements of fluorescently labelled red blood cells and of malaria parasite-infected erythrocytes expressing GFP fusions and examine other examples from the literature.
European Biophysics Journal 04/2002; 31(1):36-51. · 2.14 Impact Factor
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ABSTRACT: For more than 20 years now, Australia has been officially free of endemic malaria, but this devastating disease once again made a major impact on the continent in February 2000 when Melbourne hosted Australia's first major international conference on 'Molecular Approaches to Malaria' (Lorne, Australia, 2-5 February 2000). The global research effort toward our increased understanding of the pathogenesis and control of malaria in the post-genomics era was discussed and debated at length over 4 days packed with science encompassing molecular biology, cell biology, clinical studies, genomics, vaccines and pathogenic mechanisms. More than 260 researchers from 18 countries worldwide participated in this interdisciplinary meeting which comprised 57 oral presentations and 122 posters. Here we summarize some presentations pertinent to the field of drug action and resistance. Copyright 2000 Harcourt Publishers Ltd.
Drug resistance updates: reviews and commentaries in antimicrobial and anticancer chemotherapy 05/2000; 3(2):74-76. · 12.58 Impact Factor
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ABSTRACT: The sulfonamide and sulfone (sulfa) group of antimalarials has been used extensively throughout malaria endemic regions of the world to control this important infectious disease of humans. Sulfadoxine is the most extensively used drug of this group of drugs and is usually combined with pyrimethamine (Fansidar), particularly for the control of Plasmodium falciparum, the causative agent of the most lethal form of malaria. Resistance to the sulfadoxine/pyrimethamine combination is widespread. Analysis using molecular, genetic and biochemical approaches has shown that the mechanism of resistance to sulfadoxine involves mutation of dihydropteroate synthase, the enzyme target of this group of drugs. Understanding the mechanism of resistance of P. falciparum to sulfa drugs has allowed detailed analysis of the epidemiology of the spread of drug resistance alleles in the field(1)and, in the future, opens the way to the development of novel antimalarials to this target enzyme. Copyright 1999 Harcourt Publishers Ltd.
Drug resistance updates: reviews and commentaries in antimicrobial and anticancer chemotherapy 03/1999; 2(1):15-19. · 12.58 Impact Factor
