posttranslational modifications; motility; Toxoplasma gondii; parasite; myosins ; regulated secretion; Apicomplexa; organelle biogenesis; Plasmodium falciparum
Jacot Damien, Tosetti Nicolò, Pires Isa, Stock Jessica, Graindorge Arnault, Hung Yu-Fu, Han Huijong, Tewari Rita, Kursula Inari, Soldati-Favre Dominique (2016), An Apicomplexan Actin-Binding Protein Serves as a Connector and Lipid Sensor to Coordinate Motility and Invasion, in Cell Host & Microbe
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Bullen Hayley E., Soldati-Favre Dominique (2016), A central role for phosphatidic acid as a lipid mediator of regulated exocytosis in apicomplexa, in FEBS Letters
, 590(15), 2469-2481.
Bullen HE Jia Y Yamaryo-Botté Y Bisio H Zhang O Jemelin NK Marq JB Carruthers V Botté CY So, Bullen HE Jia Y Yamaryo-Botté Y Bisio H Zhang O Jemelin NK Marq JB Carruthers V Botté CY So, Bullen HE Jia Y Yamaryo-Botté Y Bisio H Zhang O Jemelin NK Marq JB Carruthers V Botté CY So (2016), Phosphatidic Acid-Mediated Signaling Regulates Microneme Secretion in Toxoplasma., in Cell Host Microbe
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Structural and functional dissection of Toxoplasma gondii armadillo repeats only protein. Mueller C, Structural and functional dissection of Toxoplasma gondii armadillo repeats only protein. Mueller C, Structural and functional dissection of Toxoplasma gondii armadillo repeats only protein. Mueller C (2016), Structural and functional dissection of Toxoplasma gondii armadillo repeats only protein., in J Cell Sci.
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Rugarabamu G Marq JB Guérin A Lebrun M Soldati-Favre D., Rugarabamu G Marq JB Guérin A Lebrun M Soldati-Favre D., Rugarabamu G Marq JB Guérin A Lebrun M Soldati-Favre D. (2015), Distinct contribution of Toxoplasma gondii rhomboid proteases 4 and 5 to micronemal protein protease 1 activity during invasion., in Mol Microbiol.
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Graindorge A Frénal K Jacot D Salamun J Marq JB Soldati-Favre D., Graindorge A Frénal K Jacot D Salamun J Marq JB Soldati-Favre D., Graindorge A Frénal K Jacot D Salamun J Marq JB Soldati-Favre D. (2015), The Conoid Associated Motor MyoH Is Indispensable for Toxoplasma gondii Entry and Exit from Host Cells., in PLoS Pathog
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Lamarque MH Roques M Kong-Hap M Tonkin ML Rugarabamu G Marq JB Penarete-Vargas DM Boulanger M, Lamarque MH Roques M Kong-Hap M Tonkin ML Rugarabamu G Marq JB Penarete-Vargas DM Boulanger M, Lamarque MH Roques M Kong-Hap M Tonkin ML Rugarabamu G Marq JB Penarete-Vargas DM Boulanger M (2014), Plasticity and redundancy among AMA-RON pairs ensure host cell entry of Toxoplasma parasites., in Nat Commun.
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Frénal K Marq JB Jacot D Polonais V Soldati-Favre D., Frénal K Marq JB Jacot D Polonais V Soldati-Favre D., Frénal K Marq JB Jacot D Polonais V Soldati-Favre D. (2014), Plasticity between MyoC- and MyoA-glideosomes: an example of functional compensation in Toxoplasma gondii invasion., in PLoS Pathog.
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Frénal K Tay CL Mueller C Bushell ES Jia Y Graindorge A Billker O Rayner JC Soldati-Favre D., Frénal K Tay CL Mueller C Bushell ES Jia Y Graindorge A Billker O Rayner JC Soldati-Favre D., Frénal K Tay CL Mueller C Bushell ES Jia Y Graindorge A Billker O Rayner JC Soldati-Favre D. (2013), Global analysis of apicomplexan protein S-acyl transferases reveals an enzyme essential for invasion., in Traffic
, 14(8), 895-911.
Kemp LE Yamamoto M Soldati-Favre D., Kemp LE Yamamoto M Soldati-Favre D., Kemp LE Yamamoto M Soldati-Favre D. (2013), Subversion of host cellular functions by the apicomplexan parasites, in FEMS Microbiol Rev.
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Jacot D Daher W Soldati-Favre D., Jacot D Daher W Soldati-Favre D., Jacot D Daher W Soldati-Favre D. (2013), Toxoplasma gondii myosin F, an essential motor for centrosomes positioning and apicoplast inheritance., in EMBO Journal
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SUMMARYThe major focus of our work is to decipher the molecular mechanisms underlining gliding motility and host cell invasion in the obligate intracellular parasites Toxoplasma gondii and Plasmodium spp. The multi-proteins complex called the glideosome is a unique attribute of the Apicomplexa phylum, which powers motility and critically contributes to parasite migration across biological barriers, host cell invasion and egress from infected cells. The timing, duration and orientation of gliding motility are tightly regulated to assure successful establishment of infection. The glideosome is regulated at several levels including the assembly and activity of the motor complex, which are governed by posttranslational modifications resulting at least in part from a calcium-dependent signaling cascade. Parasite motility and entry into host cells are critically assisted by the sequential discharge of specialized secretory organelles, the micronemes and the rhoptries, respectively. In T. gondii and other Coccidians (sub-group of Apicomplexa), motility and invasion also involve the concomitant protrusion of the conoid, an apical motile organelle consisting of a unique polymer of tubulin fibers coiled into a compressed helix. This proposal is in continuation with our previous line of research and aims at elucidating the mechanism of action of the glideosome and dissecting the involvement of myosin motors in rhoptry organelles biogenesis and conoid protrusion. The long-term objective is to provide a better understanding of how these complex events are orchestrated into a concerted action that culminates with the establishment of infection. Ultimately we aim to identify novel targets and approaches for intervention against this important group of humans and animal pathogens.SPECIFIC AIMS1) Architecture and Mechanism of action of the glideosomeOur recent progress in purifying an intact glideosome offers a unique opportunity to attempt a 3D reconstitution of this particle. If successful this approach will be coupled to reverse genetic manipulation of the parasites and the production of glideosome mutants in the hope to gather key information about the overall architecture of the complex as well as the interactions and functional contributions of each constituents. We will also pursue our ongoing investigations aiming at assessing the impact of post-translational modifications (phosphorylation, acylation) on glideosome assembly, localization and function.2) Mechanism of Conoid protrusion and its role in invasion and egress Conoid protrusion is a poorly understood actin-based event that is associated to extracellular parasites. We have recently identified the class XIV coccidian specific myosin H and its light chain MLC5/7 as a key motor for motility invasion and egress, which localizes to the upper ring of the conoid by high-resolution microscopy. We propose to dissect the function of this motor, map the sequence determinants responsible for its conoid localization and identify its cargo(s). We will search for partners using a variety of techniques and characterize the underlying interactions. Ultimately we hope to unravel the mechanistic implication of this motor in conoid protrusion and determine how and why this event impact on organelles discharge, motility, invasion and egress. 3) Biogenesis and discharge of regulated secretory organellesRecently, we have functionally characterized the armadillo repeat containing protein TgARO, as a key acylated protein implicated in the final step of rhoptry organelles biogenesis. We propose to dissect the structure function relationship of this protein and characterize the molecular bases of its interactions with two newly identified associated proteins, the class XXII myosin F and a large protein consisting of adenylate cyclase domains. Both of these partners are conserved across the phylum of Apicomplexa and we hypothesize that they critically participate in the apical translocation and anchoring of the organelles to the tip of the parasite, respectively. In analogy to TgARO, we have identified an acylated protein containing a PH domain and anchored at the surface of micronemes. This protein binds specifically to phosphatidic acid (PA) and while its function remains to be elucidated, it is essential for parasite survival. We hypothesize that this PA binding protein is central to membrane fusion either during organelle biogenesis or at time of discharge at the plasma membrane. EXPERIMENTAL APPROACHESWe propose to combine multidisciplinary approaches in molecular biology (transgenic parasites, site directed mutagenesis, conditional gene knockout) biochemistry (protein purification, subcellular fractionation, proteomics, interactome), structural (NMR, crystallography), and imaging (light, electron and cryo-electron microscopy). Our work also capitalizes on instrumental collaborations and will benefit from state-of-the art facilities available in ours as well as our partners’ institutions. EXPECTED VALUE OF THE PROPOSED PROJECTThis project aims at providing a better understanding of the mode of action of unconventional myosin motors implicated in the establishment of infection (gliding motility, organellar positioning and conoid protrusion). The findings that will emerge from this work are anticipated to be of significant interest to the fields embracing basic cell biology, microbiology and parasitology. Ultimately they can lead to the identification of new targets or strategies for intervention against these important human and animal pathogens.