title: Regulation of Starch Stores by a Ca(2+)-Dependent Protein Kinase Is Essential for Viable Cyst Development in Toxoplasma gondii.
abstract: Transmissible stages of Toxoplasma gondii store energy in the form of the carbohydrate amylopectin. Here, we show that the Ca(2+)-dependent protein kinase CDPK2 is a critical regulator of amylopectin metabolism. Increased synthesis and loss of degradation of amylopectin in CDPK2 deficient parasites results in the hyperaccumulation of this sugar polymer. A carbohydrate-binding module 20 (CBM20) targets CDPK2 to amylopectin stores, while the EF-hands regulate CDPK2 kinase activity in response to Ca(2+) to modulate amylopectin levels. We identify enzymes involved in amylopectin turnover whose phosphorylation is dependent on CDPK2 activity. Strikingly, accumulation of massive amylopectin granules in CDPK2-deficient bradyzoite stages leads to gross morphological defects and complete ablation of cyst formation in a mouse model. Together these data show that Ca(2+) signaling regulates carbohydrate metabolism in Toxoplasma and that the post-translational control of this pathway is required for normal cyst development.
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Victoria, 3052, Australia; Department of Medical Biology, The University of Melbourne, Victoria, 3010, Australia.
authors.forename: Alessandro D
authors.initials: AD
authors.lastname: Uboldi
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Victoria, 3052, Australia; Department of Medical Biology, The University of Melbourne, Victoria, 3010, Australia.
authors.forename: James M
authors.initials: JM
authors.lastname: McCoy
authors.affiliation: Department of Biochemistry and Molecular Biology, Bio21 Molecular Science & Biotechnology Institute, The University of Melbourne, Parkville, VIC, 3010, Australia.
authors.forename: Martin
authors.initials: M
authors.lastname: Blume
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Victoria, 3052, Australia; Department of Medical Biology, The University of Melbourne, Victoria, 3010, Australia.
authors.forename: Motti
authors.initials: M
authors.lastname: Gerlic
authors.affiliation: Nuffield Department of Clinical Laboratory Science, Oxford University, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom.
authors.forename: David J P
authors.initials: DJ
authors.lastname: Ferguson
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Victoria, 3052, Australia; Department of Medical Biology, The University of Melbourne, Victoria, 3010, Australia.
authors.forename: Laura F
authors.initials: LF
authors.lastname: Dagley
authors.affiliation: ARC Centre of Excellence in Plant Cell Walls, The School of Botany, The University of Melbourne, Victoria, 3010, Australia.
authors.forename: Cherie T
authors.initials: CT
authors.lastname: Beahan
authors.affiliation: The Department of Physiology, The University of Melbourne, Victoria, 3010, Australia.
authors.forename: David I
authors.initials: DI
authors.lastname: Stapleton
authors.affiliation: Department of Biochemistry and Molecular Biology, Bio21 Molecular Science & Biotechnology Institute, The University of Melbourne, Parkville, VIC, 3010, Australia.
authors.forename: Paul R
authors.initials: PR
authors.lastname: Gooley
authors.affiliation: ARC Centre of Excellence in Plant Cell Walls, The School of Botany, The University of Melbourne, Victoria, 3010, Australia.
authors.forename: Antony
authors.initials: A
authors.lastname: Bacic
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Victoria, 3052, Australia; Department of Medical Biology, The University of Melbourne, Victoria, 3010, Australia.
authors.forename: Seth L
authors.initials: SL
authors.lastname: Masters
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Victoria, 3052, Australia; Department of Medical Biology, The University of Melbourne, Victoria, 3010, Australia.
authors.forename: Andrew I
authors.initials: AI
authors.lastname: Webb
authors.affiliation: Department of Biochemistry and Molecular Biology, Bio21 Molecular Science & Biotechnology Institute, The University of Melbourne, Parkville, VIC, 3010, Australia.
authors.forename: Malcolm J
authors.initials: MJ
authors.lastname: McConville
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Victoria, 3052, Australia; Department of Medical Biology, The University of Melbourne, Victoria, 3010, Australia. Electronic address: tonkin@wehi.edu.au.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Tonkin
mesh_terms: D000687:Amylopectin / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D002470:Cell Survival; D017353:Gene Deletion; D051379:Mice; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D033761:Spores, Protozoan / Q000254:growth & development* / Q000378:metabolism*; D014122:Toxoplasma / Q000254:growth & development* / Q000378:metabolism*; D014124:Toxoplasmosis, Animal; D014774:Virulence
chemical_list: C490308:CDPK2 protein, Toxoplasma gondii; D002135:Calcium-Binding Proteins; D015800:Protozoan Proteins; D000687:Amylopectin; D011494:Protein Kinases; D002118:Calcium