RRC ID 29001
Author Thomason PA, Traynor D, Cavet G, Chang WT, Harwood AJ, Kay RR.
Title An intersection of the cAMP/PKA and two-component signal transduction systems in Dictyostelium.
Journal EMBO J
Abstract Terminal differentiation of both stalk and spore cells in Dictyostelium can be triggered by activation of cAMP-dependent protein kinase (PKA). A screen for mutants where stalk and spore cells mature in isolation produced three genes which may act as negative regulators of PKA: rdeC (encoding the PKA regulatory subunit), regA and rdeA. The biochemical properties of RegA were studied in detail. One domain is a cAMP phosphodiesterase (Km approximately 5 microM); the other is homologous to response regulators (RRs) of two-component signal transduction systems. It can accept phosphate from acetyl phosphate in a reaction typical of RRs, with transfer dependent on Asp212, the predicted phosphoacceptor. RegA phosphodiesterase activity is stimulated up to 8-fold by the phosphodonor phosphoramidate, with stimulation again dependent on Asp212. This indicates that phosphorylation of the RR domain activates the phosphodiesterase domain. Overexpression of the RR domain in wild-type cells phenocopies a regA null. We interpret this dominant-negative effect as due to a diversion of the normal flow of phosphates from RegA, thus preventing its activation. Mutation of rdeA is known to produce elevated cAMP levels. We propose that cAMP breakdown is controlled by a phosphorelay system which activates RegA, and may include RdeA. Cell maturation should be triggered when this system is inhibited.
Volume 17(10)
Pages 2838-45
Published 1998-5-15
DOI 10.1093/emboj/17.10.2838
PMID 9582277
PMC PMC1170624
MeSH 3',5'-Cyclic-AMP Phosphodiesterases / genetics 3',5'-Cyclic-AMP Phosphodiesterases / metabolism* Animals Base Sequence Binding Sites Cyclic AMP-Dependent Protein Kinases / genetics Cyclic AMP-Dependent Protein Kinases / metabolism* DNA, Fungal Dictyostelium / enzymology* Dictyostelium / genetics Enzyme Activation Molecular Sequence Data Mutation Phosphates / metabolism Phosphorylation Protozoan Proteins* Signal Transduction* Spores, Fungal
IF 11.227
Times Cited 110
Cellular slime molds S00141 S00482