In Dictyostelium discoideum, the chemoattractant cyclic AMP activates the enzyme guanylate cyclase, giving a brief up to 10-fold increase in the intracellular cyclic GMP content. The addition of physiological cyclic GMP concentrations to a homogenate of D. discoideum cells markedly increased the incorporation of the 3H-labeled methyl group from S-adenosyl-L-[methyl-3H]methionine into mono- and dimethylated phosphatidylethanolamine and phosphatidylcholine. Lipid methylation was inhibited by S-adenosyl-L-homocysteine, which inhibits transmethylation. When whole cells prelabeled with L-[methyl-3H]methionine were exposed to cyclic AMP, a rapid transient increase in the amount of [methyl-3H]phosphatidylcholine was observed. The time course of [methyl-3H]phosphatidylcholine formation agrees with its being mediated by the intracellular increase in cyclic GMP originating during chemotactic stimulation. Addition of the 8-Br derivative of cyclic GMP to whole cells also increased the levels of labeled phosphatidylcholine. It is therefore likely that cyclic GMP contributes to chemotaxis by regulating membrane function via phospholipid methylation.
Regulation by cGMP of phospholipid methylation during chemitaxis in D. discoideum.
GARCIA GIL, MARIA de las MERCEDES;
1980-01-01
Abstract
In Dictyostelium discoideum, the chemoattractant cyclic AMP activates the enzyme guanylate cyclase, giving a brief up to 10-fold increase in the intracellular cyclic GMP content. The addition of physiological cyclic GMP concentrations to a homogenate of D. discoideum cells markedly increased the incorporation of the 3H-labeled methyl group from S-adenosyl-L-[methyl-3H]methionine into mono- and dimethylated phosphatidylethanolamine and phosphatidylcholine. Lipid methylation was inhibited by S-adenosyl-L-homocysteine, which inhibits transmethylation. When whole cells prelabeled with L-[methyl-3H]methionine were exposed to cyclic AMP, a rapid transient increase in the amount of [methyl-3H]phosphatidylcholine was observed. The time course of [methyl-3H]phosphatidylcholine formation agrees with its being mediated by the intracellular increase in cyclic GMP originating during chemotactic stimulation. Addition of the 8-Br derivative of cyclic GMP to whole cells also increased the levels of labeled phosphatidylcholine. It is therefore likely that cyclic GMP contributes to chemotaxis by regulating membrane function via phospholipid methylation.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
