title: A forward genetic screen identifies a negative regulator of rapid Ca2+-dependent cell egress (MS1) in the intracellular parasiteToxoplasma gondii.
abstract: Toxoplasma gondii, like all apicomplexan parasites, uses Ca2+signaling pathways to activate gliding motility to power tissue dissemination and host cell invasion and egress. A group of "plant-like" Ca2+-dependent protein kinases (CDPKs) transduces cytosolic Ca2+flux into enzymatic activity, but how they function is poorly understood. To investigate how Ca2+signaling activates egress through CDPKs, we performed a forward genetic screen to isolate gain-of-function mutants from an egress-deficientcdpk3knockout strain. We recovered mutants that regained the ability to egress from host cells that harbored mutations in the geneSuppressor of Ca2+-dependent Egress 1(SCE1). Global phosphoproteomic analysis showed that SCE1 deletion restored many Δcdpk3-dependent phosphorylation events to near wild-type levels. We also show that CDPK3-dependent SCE1 phosphorylation is required to relieve its suppressive activity to potentiate egress. In summary, our work has uncovered a novel component and suppressor of Ca2+-dependent cell egress duringToxoplasmalytic growth.
authors.affiliation: From the Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria 3052, Australia.|the Departments of Medical Biology.|Computing and Information Systems,University of Melbourne, Victoria 3010, Australia.
authors.forename: James M
authors.initials: JM
authors.lastname: McCoy
authors.affiliation: From the Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria 3052, Australia.|the Departments of Medical Biology.|Computing and Information Systems,University of Melbourne, Victoria 3010, Australia.
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Stewart
authors.affiliation: From the Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria 3052, Australia.|the Departments of Medical Biology.|Computing and Information Systems,University of Melbourne, Victoria 3010, Australia.
authors.forename: Alessandro D
authors.initials: AD
authors.lastname: Uboldi
authors.affiliation: the Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia.
authors.forename: Dongdi
authors.initials: D
authors.lastname: Li
authors.affiliation: From the Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria 3052, Australia.|the Departments of Medical Biology.|the Peter MacCallum Cancer Institute, Victoria 3000, Australia, and.
authors.forename: Jan
authors.initials: J
authors.lastname: Schröder
authors.affiliation: the University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
authors.forename: Nicollas E
authors.initials: NE
authors.lastname: Scott
authors.affiliation: From the Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria 3052, Australia.|the Departments of Medical Biology.|the Peter MacCallum Cancer Institute, Victoria 3000, Australia, and.
authors.forename: Anthony T
authors.initials: AT
authors.lastname: Papenfuss
authors.affiliation: the Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia.
authors.forename: Adele M
authors.initials: AM
authors.lastname: Lehane
authors.affiliation: the University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
authors.forename: Leonard J
authors.initials: LJ
authors.lastname: Foster
authors.affiliation: From the Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria 3052, Australia, tonkin@wehi.edu.au.|the Departments of Medical Biology.
authors.forename: Christopher J
authors.identifier: 0000-0002-7036-6222
authors.initials: CJ
authors.lastname: Tonkin
mesh_terms: D020013:Calcium Signaling / Q000502:physiology*; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000502:physiology; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D014122:Toxoplasma / Q000235:genetics / Q000378:metabolism*
chemical_list: D002135:Calcium-Binding Proteins; D015800:Protozoan Proteins; D011494:Protein Kinases
keywords: Ca2+ signalling; Toxoplasma gondii; apicomplexa; forward genetic screen; host cell egress; molecular genetics; parasite; proteomics; signaling