Functional Dissection of the Apicomplexan Glideosome Molecular Architecture

Department of Microbiology and Molecular Medicine, Centre Medical Universitaire, University of Geneva, CH-1211 Geneva 4, Switzerland.
Cell host & microbe (Impact Factor: 12.19). 10/2010; 8(4):343-57. DOI: 10.1016/j.chom.2010.09.002
Source: PubMed

ABSTRACT The glideosome of apicomplexan parasites is an actin- and myosin-based machine located at the pellicle, between the plasma membrane (PM) and inner membrane complex (IMC), that powers parasite motility, migration, and host cell invasion and egress. It is composed of myosin A, its light chain MLC1, and two gliding-associated proteins, GAP50 and GAP45. We identify GAP40, a polytopic protein of the IMC, as an additional glideosome component and show that GAP45 is anchored to the PM and IMC via its N- and C-terminal extremities, respectively. While the C-terminal region of GAP45 recruits MLC1-MyoA to the IMC, the N-terminal acylation and coiled-coil domain preserve pellicle integrity during invasion. GAP45 is essential for gliding, invasion, and egress. The orthologous Plasmodium falciparum GAP45 can fulfill this dual function, as shown by transgenera complementation, whereas the coccidian GAP45 homolog (designated here as) GAP70 specifically recruits the glideosome to the apical cap of the parasite.

  • [Show abstract] [Hide abstract]
    ABSTRACT: To survive and persist within its human host, the malaria parasite P. falciparum utilizes a battery of lineage-specific innovations to invade and multiply in human erythrocytes. With central roles in invasion and cytokinesis, the inner membrane complex, a Golgi derived double membrane structure underlying the plasma membrane of the parasite, represents a unique and unifying structure characteristic to all organisms belonging to a large phylogenetic group called Alveolata. More than 30 structurally and phylogenetically distinct proteins are embedded in the IMC membranes, where a portion of these proteins displays N-terminal acylation motifs. While N-terminal myristoylation is catalyzed co-translationally within the cytoplasm of the parasite, palmitoylation takes place at membranes and is mediated by palmitoyl acyltransferases (PATs). Here, we identify a PAT (PfDHHC1) that is exclusively localized to the IMC. Systematic phylogenetic analysis of the alveolate PAT family reveals PfDHHC1 to be a member of a highly conserved, apicomplexan-specific clade of PATs. We show that during schizogony this enzyme has an identical distribution like two, dual acylated, IMC localized proteins (PfISP1 and PfISP3). We used these proteins to probe into specific sequence requirements for IMC specific membrane recruitment, and their interaction with differentially localized PATs of the parasite. Copyright © 2014, The American Society for Biochemistry and Molecular Biology.
    Journal of Biological Chemistry 11/2014; 290(3). DOI:10.1074/jbc.M114.598094 · 4.60 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Myosin B (MyoB) is one of the two short class XIV myosins encoded in the Plasmodium genome. Class XIV myosins are characterised by a catalytic head, a modified neck region and the absence of a tail region. Myosin A (MyoA), the other class XIV myosin in Plasmodium, has been established as a component of the glideosome complex important in motility and cell invasion but MyoB is not well characterised. We analysed the properties of MyoB using three parasite species: P. falciparum, P. berghei and P. knowlesi. MyoB is expressed in all invasive stages (merozoites, ookinetes and sporozoites) of the life cycle and the protein is found in a discrete apical location in these polarised cells. In P. falciparum, MyoB is synthesised very late in schizogony/merogony and its location in merozoites is distinct from, and anterior to, that of a range of known proteins present in the rhoptries, rhoptry neck or micronemes. Unlike MyoA, MyoB is not associated with glideosome complex proteins, including the MyoA light chain, Myosin A tail domain interacting protein (MTIP). A unique MyoB light chain (MLC-B) was identified that contains a calmodulin-like domain at the C-terminus and an extended N-terminal region. MLC-B localises to the same extreme apical pole in the cell as MyoB and the two proteins form a complex. We propose that MLC-B is a MyoB-specific light chain and that for the short class XIV myosins that lack a tail region, the atypical myosin light chains may fulfil that role. Copyright © 2015, The American Society for Biochemistry and Molecular Biology.
    Journal of Biological Chemistry 03/2015; 290(19). DOI:10.1074/jbc.M115.637694 · 4.60 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Hemoglobin degradation during the asexual cycle of Plasmodium falciparum is an obligate process for parasite development and survival. It is established that hemoglobin is transported from the host erythrocyte to the parasite digestive vacuole (DV), but this biological process is not well characterized. Three-dimensional reconstructions made from serial, thin-section, electron micrographs of untreated, trophozoite stage P. falciparum infected erythrocytes (IRBC) or IRBC treated with different pharmacological agents provide new insight into the organization and regulation of the hemoglobin transport pathway. Hemoglobin internalization commences with the formation of cytostomes from localized, electron-dense collars at the interface of the parasite plasma- and parasitophorous vacuolar- membranes. The cytostomal collar does not function as a site of vesicle fission, but rather serves to stabilize the maturing cytostome. We provide the first evidence that hemoglobin transport to the DV utilizes an actin-myosin motor system. Short-lived, hemoglobin-filled vesicles form from the distal end of the cytostomes, through actin and dynamin-mediated processes. Results from IRBC treated with N-ethylmaleimide (NEM) suggest that fusion of hemoglobin containing vesicles with the DV may involve a SNARE- dependent mechanism. In this investigation, we identify new key components of the hemoglobin transport pathway and provide a detailed characterization of its morphological organization and regulation. Copyright © 2015, American Society for Microbiology. All Rights Reserved.
    Eukaryotic Cell 02/2015; 14(4). DOI:10.1128/EC.00267-14 · 3.18 Impact Factor