title: Adenylyl cyclase G, an osmosensor controlling germination of Dictyostelium spores.
abstract: Dictyostelium cells express a G-protein-coupled adenylyl cyclase, ACA, during aggregation and an atypical adenylyl cyclase, ACG, in mature spores. The ACG gene was disrupted by homologous recombination. acg- cells developed into normal fruiting bodies with viable spores, but spore germination was no longer inhibited by high osmolarity, a fairly universal constraint for spore and seed germination. ACG activity, measured in aca-/ACG cells, was strongly stimulated by high osmolarity with optimal stimulation occurring at 200 milliosmolar. RdeC mutants, which display unrestrained protein kinase A (PKA) activity and a cell line, which overexpresses PKA under a prespore specific promoter, germinate very poorly, both at high and low osmolarity. These data indicate that ACG is an osmosensor controlling spore germination through activation of protein kinase A.
authors.affiliation: Cell Biology Section, Institute for Molecular Plant Sciences, University of Leiden, Wassenaarseweg 64, 2333AL Leiden, The Netherlands.
authors.forename: S
authors.initials: S
authors.lastname: van Es
authors.forename: K J
authors.initials: KJ
authors.lastname: Virdy
authors.forename: G S
authors.initials: GS
authors.lastname: Pitt
authors.forename: M
authors.initials: M
authors.lastname: Meima
authors.forename: T W
authors.initials: TW
authors.lastname: Sands
authors.forename: P N
authors.initials: PN
authors.lastname: Devreotes
authors.forename: D A
authors.initials: DA
authors.lastname: Cotter
authors.forename: P
authors.initials: P
authors.lastname: Schaap
mesh_terms: D000262:Adenylyl Cyclases / Q000502:physiology*; D000818:Animals; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology; D004023:Dictyostelium / Q000201:enzymology* / Q000502:physiology; D005656:Fungal Proteins / Q000502:physiology*; D016254:Mutagenesis, Insertional; D015800:Protozoan Proteins; D015398:Signal Transduction; D013172:Spores, Fungal / Q000502:physiology*; D014882:Water-Electrolyte Balance
chemical_list: D005656:Fungal Proteins; D015800:Protozoan Proteins; D017868:Cyclic AMP-Dependent Protein Kinases; C101765:ACG protein, Dictyostelium discoideum; D000262:Adenylyl Cyclases