Molecular Strategies for Active Host Cell Invasion by Apicomplexan Parasites

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dc.contributor.author Tonkin, Michelle Lorine
dc.date.accessioned 2014-07-28T23:05:28Z
dc.date.available 2015-05-31T11:22:04Z
dc.date.copyright 2014 en_US
dc.date.issued 2014-07-28
dc.identifier.uri http://hdl.handle.net/1828/5496
dc.description.abstract Parasites of phylum Apicomplexa cause devastating diseases on a global scale. Toxoplasma gondii, the etiological agent of toxoplasmosis, and Plasmodium falciparum, the most virulent agent of human malaria, have the most substantial effects on human health and are the most widely studied. The success of these parasites is due in part to a sophisticated molecular arsenal that supports a variety of novel biological processes including a unique form of host cell invasion. Accessing the protective environment of the host cell is paramount to parasite survival and is mediated through an active invasion process: the parasite propels itself through a circumferential ring known as the moving junction (MJ) formed between its apical tip and the host cell membrane. The MJ ring is comprised of a parasite surface protein (AMA1) that engages a protein secreted by the parasite into the host cell and presented on the host cell surface (RON2). Thus, through an intriguing mechanism the parasite provides both receptor and ligand to enable host cell invasion. Prior to the studies described herein, the characterization of the AMA1-RON2 association was limited to low-resolution experiments that provided little insight into the functional and architectural details of this crucial binary complex. Towards elucidating the mechanism of AMA1-RON2 dependent invasion, I first structurally characterized T. gondii AMA1 bound to the corresponding binding region of RON2; analysis of the AMA1-RON2 interface along with biophysical data revealed an intimate association likely capable of withstanding the shearing forces generated as the parasite dives through the constricted MJ ring. To investigate the role of the AMA1-RON2 complex across genera, species and life-cycle stages, I next characterized the AMA1-RON2 complex from a distantly related genus within Apicomplexa (Plasmodium) and from a divergent pairing within T. gondii. By combining structural, biophysical and biological data, I was able to generate a detailed model describing the role of AMA1 and RON2 in MJ dependent invasion, which is currently supporting efforts to develop novel vaccines and cross-reactive small molecule therapeutics. en_US
dc.language.iso en en_US
dc.subject X-ray crystallography en_US
dc.subject Host-pathogen interactions en_US
dc.subject Protein purification en_US
dc.subject Protein production en_US
dc.subject Protein crystallization en_US
dc.subject Apicomplexa en_US
dc.title Molecular Strategies for Active Host Cell Invasion by Apicomplexan Parasites en_US
dc.type Thesis en_US
dc.contributor.supervisor Boulanger, Martin J.
dc.degree.department Department of Biochemistry and Microbiology en_US
dc.degree.level Doctor of Philosophy Ph.D. en_US
dc.rights.temp Available to the World Wide Web en_US
dc.identifier.bibliographicCitation Tonkin, M. L., M. Roques, M. H. Lamarque, M. Pugniere, D. Douguet, J. Crawford, M. Lebrun and M. J. Boulanger (2011). “Host cell invasion by apicomplexan parasites: insights from the co-structure of AMA1 with a RON2 peptide.” Science 333(6041): 463-467. en_US
dc.identifier.bibliographicCitation Vulliez-Le Normand, B., M. L. Tonkin, M. H. Lamarque, S. Langer, S. Hoos, M. Roques, F. A. Saul, B. W. Faber, G. A. Bentley, M. J. Boulanger and M. Lebrun (2012). “Structural and functional insights into the malaria parasite moving junction complex.” PLoS Pathogens 8(6): e1002755. en_US
dc.identifier.bibliographicCitation Poukchanski, A., H. M. Fritz, M. L. Tonkin, M. Treeck, M. J. Boulanger and J. C. Boothroyd (2013). “Toxoplasma gondii sporozoites invade host cells using two novel paralogues of RON2 and AMA1.” PLoS One 8(8): e70637. en_US
dc.description.scholarlevel Graduate en_US
dc.description.proquestcode 0487 en_US

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