Role of phospholipase C in Dictyostelium: formation of inositol 1,4,5-trisphosphate and normal development in cells lacking phospholipase C activity.
The micro-organism Dictyostelium uses extracellular cAMP to induce chemotaxis and cell differentiation. Signals are transduced via surface receptors, which activate G proteins, to effector enzymes. The deduced protein sequence of Dictyostelium discoideum phosphatidylinositol-specific phospholipase C (PLC) shows strong homology with the mammalian PLC-delta isoforms. To study the role of PLC in Dictyostelium, a plc- mutant was constructed by disruption of the PLC gene. No basal or stimulated PLC activity could be measured during the whole developmental programme of the plc- cells. Loss of PLC activity did not result in a visible alteration of growth or development. Further analysis showed that developmental gene regulation, cAMP-mediated chemotaxis and activation of guanylyl and adenylyl cyclase were normal. Although the cells lack PLC activity, inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] was present at only slightly lower concentrations compared with control cells. Mass analysis of inositol phosphates demonstrated the presence of a broad spectrum of inositol phosphates in Dictyostelium, which was unaltered in the plc- mutant. Cell labelling experiments with [3H]inositol indicated that [3H]Ins(1,4,5)P3 was formed in a different manner in the mutant than in control cells.
Drayer
A L
AL
Department of Biochemistry, University of Groningen, The Netherlands.
Van der Kaay
J
J
Mayr
G W
GW
Van Haastert
P J
PJ
D000818:Animals; D002454:Cell Differentiation; D002633:Chemotaxis / Q000502:physiology*; D000242:Cyclic AMP / Q000494:pharmacology; D004023:Dictyostelium / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D015544:Inositol 1,4,5-Trisphosphate / Q000096:biosynthesis*; D007295:Inositol Phosphates / Q000032:analysis; D009154:Mutation; D015290:Second Messenger Systems; D015398:Signal Transduction; D010738:Type C Phospholipases / Q000502:physiology*
D007295:Inositol Phosphates; D015544:Inositol 1,4,5-Trisphosphate; D000242:Cyclic AMP; D010738:Type C Phospholipases