A Toxoplasma gondii Gluconeogenic Enzyme Contributes to Robust Central Carbon Metabolism and Is Essential for Replication and Virulence.
The expression of gluconeogenic enzymes is typically repressed when glucose is available. The protozoan parasite Toxoplasma gondii utilizes host glucose to sustain high rates of intracellular replication. However, despite their preferential utilization of glucose, intracellular parasites constitutively express two isoforms of the gluconeogenic enzyme fructose 1,6-bisphosphatase (TgFBP1 and TgFBP2). The rationale for constitutive expression of FBPases in T. gondii remains unclear. We find that conditional knockdown of TgFBP2 results in complete loss of intracellular growth in vitro under glucose-replete conditions and loss of acute virulence in mice. TgFBP2 deficiency was rescued by expression of catalytically active FBPase and was associated with altered glycolytic and mitochondrial TCA cycle fluxes, as well as dysregulation of glycolipid, amylopectin, and fatty acid biosynthesis. Futile cycling between gluconeogenic and glycolytic enzymes may constitute a regulatory mechanism that allows T. gondii to rapidly adapt to changes in nutrient availability in different host cells.
Department of Biochemistry and Molecular Biology, Bio21 Institute of Molecular Science and Biotechnology, The University of Melbourne, Parkville, VIC 3010, Australia.
Martin
M
Blume
Department of Molecular Parasitology, Humboldt University, Berlin 10115, Germany.
Richard
R
Nitzsche
Department of Molecular Parasitology, Humboldt University, Berlin 10115, Germany.
Ulrich
U
Sternberg
Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, and Department of Medical Biology, The University of Melbourne, Parkville, VIC 3010, Australia; Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.
Motti
M
Gerlic
Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, and Department of Medical Biology, The University of Melbourne, Parkville, VIC 3010, Australia.
Seth L
SL
Masters
Department of Molecular Parasitology, Humboldt University, Berlin 10115, Germany.
Nishith
N
Gupta
Department of Biochemistry and Molecular Biology, Bio21 Institute of Molecular Science and Biotechnology, The University of Melbourne, Parkville, VIC 3010, Australia. Electronic address: malcolmm@unimelb.edu.au.
Malcolm J
MJ
McConville
D000687:Amylopectin / Q000032:analysis; D000818:Animals; D002244:Carbon / Q000378:metabolism*; D002952:Citric Acid Cycle; D004195:Disease Models, Animal; D005227:Fatty Acids / Q000032:analysis; D006597:Fructose-Bisphosphatase / Q000235:genetics / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D005816:Genetic Complementation Test; D005947:Glucose / Q000378:metabolism*; D006017:Glycolipids / Q000032:analysis; D064688:Metabolic Flux Analysis; D051379:Mice; D014122:Toxoplasma / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014124:Toxoplasmosis, Animal / Q000469:parasitology / Q000473:pathology; D014774:Virulence
D005227:Fatty Acids; D006017:Glycolipids; D002244:Carbon; D000687:Amylopectin; D006597:Fructose-Bisphosphatase; D005947:Glucose