ORCID Profile
0000-0001-9118-5079
Current Organisation
Institut Pasteur
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Publisher: Oxford University Press (OUP)
Date: 03-03-2012
Abstract: The inner membrane complex (IMC) is a unifying morphological feature of all alveolate organisms. It consists of flattened vesicles underlying the plasma membrane and is interconnected with the cytoskeleton. Depending on the ecological niche of the organisms, the function of the IMC ranges from a fundamental role as reinforcement system to more specialized roles in motility and cytokinesis. In this article, we present a comprehensive evolutionary analysis of IMC components, which exemplifies the adaptive nature of the IMCs' protein composition. Focusing on eight structurally distinct proteins in the most prominent "genus" of the Alveolata-the malaria parasite Plasmodium-we demonstrate that the level of conservation is reflected in phenotypic characteristics, accentuated in differential spatial-temporal patterns of these proteins in the motile stages of the parasite's life cycle. Colocalization studies with the centromere and the spindle apparatus reveal their discriminative biogenesis. We also reveal that the IMC is an essential structural compartment for the development of the sexual stages of Plasmodium, as it seems to drive the morphological changes of the parasite during the long and multistaged process of sexual differentiation. We further found a Plasmodium-specific IMC membrane matrix protein that highlights transversal structures in gametocytes, which could represent a genus-specific structural innovation required by Plasmodium. We conclude that the IMC has an additional role during sexual development supporting morphogenesis of the cell, which in addition to its functions in the asexual stages highlights the multifunctional nature of the IMC in the Plasmodium life cycle.
Publisher: Elsevier BV
Date: 06-2009
DOI: 10.1016/J.IJPARA.2008.12.004
Abstract: Proteins on the surface of the merozoite, the invasive form of the malaria parasite Plasmodium falciparum,and those secreted from its apical secretory organelles are promising vaccine candidates against blood stage malaria. In the present study, we have identified a novel parasite protein (PfDBLMSP Gene IDPF10_0348), that harbors a predicted signal sequence, a central Duffy binding-like (DBL) domain and a secreted polymorphic antigen associated with merozoites (SPAM) domain in its C-terminal half. Transcription and translation of pfdblmsp is up-regulated specifically in schizont stage parasites, similar to other well-chararacterized merozoite proteins involved in invasion of red blood cells (RBCs). PfDBLMSPwas localized on the merozoite surface with a GFP targeting approach using schizont-stage specific expression systems, and by immunofluorescence assays of the endogenous protein. PfDBLMSP expressed on the surface of mammalian cells (COS-7) showed binding with human RBCs and this binding was sensitive to trypsin and neuraminidase treatments. The recombinant proteins corresponding to the DBL and SPAM domains showed reactivity with immune sera from in iduals residing in P. falciparum endemic areas. Polymorphism in PfDBLMSP sequences from different P. falciparum strains and field isolates suggested that its DBL domain is under natural immune pressure. Our data on localization and functional assays suggest a possible role of PfDBLMSP in binding of merozoites with erythrocytes during invasion.
No related grants have been discovered for Dipto Sinha.