title: Disruption of inositol biosynthesis through targeted mutagenesis in Dictyostelium discoideum: generation and characterization of inositol-auxotrophic mutants.
abstract: myo-Inositol and its downstream metabolites participate in diverse physiological processes. Nevertheless, considering their variety, it is likely that additional roles are yet to be uncovered. Biosynthesis of myo-inositol takes place via an evolutionarily conserved metabolic pathway and is strictly dependent on inositol-3-phosphate synthase (EC 5.5.1.4). Genetic manipulation of this enzyme will disrupt the cellular inositol supply. Two methods, based on gene deletion and antisense strategy, were used to generate mutants of the cellular slime mould Dictyostelium discoideum. These mutants are inositol-auxotrophic and show phenotypic changes under inositol starvation. One remarkable attribute is their inability to live by phagocytosis of bacteria, which is the exclusive nutrient source in their natural environment. Cultivated on fluid medium, the mutants lose their viability when deprived of inositol for longer than 24 h. Here, we report a study of the alterations in the first 24 h in cellular inositol, inositol phosphate and phosphoinositide concentrations, whereby a rapidly accumulating phosphorylated compound was detected. After its identification as 2,3-BPG (2,3-bisphosphoglycerate), evidence could be found that the internal disturbances of inositol homoeostasis trigger the accumulation. In a first attempt to characterize this as a physiologically relevant response, the efficient in vitro inhibition of a D. discoideum inositol-polyphosphate 5-phosphatase (EC 3.1.3.56) by 2,3-BPG is presented.
authors.affiliation: Fachbereich C-Biochemie, Bergische Universität Wuppertal, Gaussstrasse 20, D-42119 Wuppertal, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Fischbach
authors.forename: Stephan
authors.initials: S
authors.lastname: Adelt
authors.forename: Alexander
authors.initials: A
authors.lastname: Müller
authors.forename: Günter
authors.initials: G
authors.lastname: Vogel
mesh_terms: D019794:2,3-Diphosphoglycerate / Q000378:metabolism; D000818:Animals; D002470:Cell Survival; D004023:Dictyostelium / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D007294:Inositol / Q000096:biosynthesis*; D007295:Inositol Phosphates / Q000378:metabolism; D000072181:Inositol Polyphosphate 5-Phosphatases; D009154:Mutation; D010587:Phagocytosis; D010716:Phosphatidylinositols / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000037:antagonists & inhibitors; D010873:Pinocytosis
chemical_list: D007295:Inositol Phosphates; D010716:Phosphatidylinositols; D019794:2,3-Diphosphoglycerate; D007294:Inositol; D010744:Phosphoric Monoester Hydrolases; D000072181:Inositol Polyphosphate 5-Phosphatases