title: Phosphorylation of αSNAP is Required for Secretory Organelle Biogenesis in Toxoplasma gondii.
abstract: Upon infection, apicomplexan parasites quickly invade host cells and begin a replicative cycle rapidly increasing in number over a short period of time, leading to tissue lysis and disease. The secretory pathway of these highly polarized protozoan parasites tightly controls, in time and space, the biogenesis of specialized structures and organelles required for invasion and intracellular survival. In other systems, regulation of protein trafficking can occur by phosphorylation of vesicle fusion machinery. Previously, we have shown that Toxoplasma gondii αSNAP - a protein that controls the disassembly of cis-SNARE complexes--is phosphorylated. Here, we show that this post-translational modification is required for the correct function of αSNAP in controlling secretory traffic. We demonstrate that during intracellular development conditional expression of a non-phosphorylatable form of αSNAP results in Golgi fragmentation and vesiculation of all downstream secretory organelles. In addition, we show that the vestigial plastid (termed apicoplast), although reported not to be reliant on Golgi trafficking for biogenesis, is also affected upon overexpression of αSNAP and is much more sensitive to the levels of this protein than targeting to other organelles. This work highlights the importance of αSNAP and its phosphorylation in Toxoplasma organelle biogenesis and exposes a hereto fore-unexplored mechanism of regulation of vesicle fusion during secretory pathway trafficking in apicomplexan parasites.
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, Melbourne, 3052, Australia.|The Department of Medical Biology, The University of Melbourne, Melbourne, 3010, Australia.
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Stewart
authors.affiliation: Nuffield Department of Clinical Laboratory Science, Oxford University, John Radcliffe Hospital, Oxford, OX3 9DU, UK.
authors.forename: David J P
authors.initials: DJ
authors.lastname: Ferguson
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, Melbourne, 3052, Australia.
authors.forename: Lachlan
authors.initials: L
authors.lastname: Whitehead
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, Melbourne, 3052, Australia.
authors.forename: Clare H
authors.initials: CH
authors.lastname: Bradin
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, Melbourne, 3052, Australia.|The Department of Medical Biology, The University of Melbourne, Melbourne, 3010, Australia.
authors.forename: Hong J
authors.initials: HJ
authors.lastname: Wu
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, Melbourne, 3052, Australia.|The Department of Medical Biology, The University of Melbourne, Melbourne, 3010, Australia.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Tonkin
mesh_terms: D006056:Golgi Apparatus / Q000502:physiology; D001678:Organelle Biogenesis; D015388:Organelles / Q000378:metabolism* / Q000502:physiology; D010766:Phosphorylation / Q000502:physiology*; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D021381:Protein Transport / Q000502:physiology; D015800:Protozoan Proteins / Q000378:metabolism; D055571:Secretory Pathway / Q000502:physiology*; D052067:Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins / Q000378:metabolism*; D014122:Toxoplasma / Q000378:metabolism* / Q000502:physiology
chemical_list: D015800:Protozoan Proteins; D052067:Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins
keywords: organelle biogenesis; phosphorylation; trafficking; αSNAP