Developmental regulation of the inositol 1,4,5-trisphosphate phosphatases in Dictyostelium discoideum.
The cellular slime mold Dictyostelium discoideum is a microorganism in which growth and development are strictly separated. Starvation initiates a developmental program in which extracellular cAMP plays a major role as a signal molecule. In response to cAMP several second messengers are produced, including cAMP, cGMP and inositol 1,4,5-trisphosphate, (Ins(1,4,5)P3). Ins(1,4,5)P3 levels are controlled by the activation of phosphoinositidase C and the activity of the Ins(1,4,5)P3-degrading phosphatases. In Dictyostelium discoideum two major routes for the dephosphorylation of Ins(1,4,5)P3 are present: a 5-phosphatase, which hydrolyses Ins(1,4,5)P3 at the 5-position producing Ins(1,4)P2 as in vertebrate cells, and a 1-phosphatase which removes the 1-phosphate, giving Ins(4,5)P2, as in plants. In this paper we show that at the onset of development both the 1-phosphatase and the 5-phosphatase are present in equal amounts. During development the 5-phosphatase disappears leaving the 1-phosphatase as the single enzyme to remove Ins(1,4,5)P3. We conclude that during development Dictyostelium discoideum switches from a mixed type of Ins(1,4,5)P3 degradation to a more plant-like degradation pathway.
Bominaar
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AA
Department of Biochemistry, University of Groningen, The Netherlands.
Van Dijken
P
P
Draijer
R
R
Van Haastert
P J
PJ
D002852:Chromatography, Ion Exchange; D004023:Dictyostelium / Q000201:enzymology / Q000254:growth & development*; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D007700:Kinetics; D008954:Models, Biological; D010744:Phosphoric Monoester Hydrolases / Q000302:isolation & purification / Q000378:metabolism*; D015290:Second Messenger Systems
D015544:Inositol 1,4,5-Trisphosphate; C035215:inositol triphosphate phosphomonoesterase; D010744:Phosphoric Monoester Hydrolases