Regulation of Starch Stores by a Ca(2+)-Dependent Protein Kinase Is Essential for Viable Cyst Development in Toxoplasma gondii

• Published in: Cell host & microbe Vol. 18; no. 6; pp. 670 - 681
• Main Authors: Uboldi, Alessandro D, McCoy, James M, Blume, Martin, Gerlic, Motti, Ferguson, David J P, Dagley, Laura F, Beahan, Cherie T, Stapleton, David I, Gooley, Paul R, Bacic, Antony, Masters, Seth L, Webb, Andrew I, McConville, Malcolm J, Tonkin, Christopher J
• Format: Journal Article
• Language: English
• Published: United States 09.12.2015
• Subjects: Amylopectin - metabolism; Animals; Calcium - metabolism; Calcium-Binding Proteins - genetics; Calcium-Binding Proteins - metabolism; Cell Survival; Gene Deletion; Mice; Protein Kinases - genetics; Protein Kinases - metabolism; Protozoan Proteins - genetics; Protozoan Proteins - metabolism; Spores, Protozoan - growth & development; Spores, Protozoan - metabolism; Toxoplasma - growth & development; Toxoplasma - metabolism; Toxoplasmosis, Animal; Virulence
• DOI: 10.1016/j.chom.2015.11.004

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.