A novel cytosolic regulator, Pianissimo, is required for chemoattractant receptor and G protein-mediated activation of the 12 transmembrane domain adenylyl cyclase in Dictyostelium.
Genetic analysis was applied to identify novel genes involved in G protein-linked pathways controlling development. Using restriction enzyme-mediated integration (REMI), we have identified a new gene, Pianissimo (PiaA), involved in cAMP signaling in Dictyostelium discoideum. PiaA encodes a 130-kD cytosolic protein required for chemoattractant receptor and G protein-mediated activation of the 12 transmembrane domain adenylyl cyclase. In piaA- null mutants, neither chemoattractant stimulation of intact cells nor GTPgammaS treatment of lysates activates the enzyme; constitutive expression of PiaA reverses these defects. Cytosols of wild-type cells that contain Pia protein reconstitute the GTPgammaS stimulation of adenylyl cyclase activity in piaA- lysates, indicating that Pia is directly involved in the activation. Pia and CRAC, a previously identified cytosolic regulator, are both essential for activation of the enzyme as lysates of crac- piaA- double mutants require both proteins for reconstitution. Homologs of PiaA are found in Saccharomyces cerevisiae and Schizosaccaromyces pombe; disruption of the S. cerevisiae homolog results in lethality. We propose that homologs of Pia and similar modes of regulation of these ubiquitous G protein-linked pathways are likely to exist in higher eukaryotes.
Chen
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Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205-2185, USA.
Long
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Devreotes
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D000199:Actins / Q000378:metabolism; D000262:Adenylyl Cyclases / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D002630:Chemotactic Factors / Q000378:metabolism*; D002633:Chemotaxis; D003001:Cloning, Molecular; D006152:Cyclic GMP / Q000096:biosynthesis; D003600:Cytosol / Q000378:metabolism; D004023:Dictyostelium / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D015870:Gene Expression; D005800:Genes, Fungal; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism* / Q000494:pharmacology; D008969:Molecular Sequence Data; D015800:Protozoan Proteins; D012441:Saccharomyces cerevisiae / Q000235:genetics; D012568:Schizosaccharomyces / Q000235:genetics; D017386:Sequence Homology, Amino Acid
D000199:Actins; D002630:Chemotactic Factors; D005656:Fungal Proteins; C109557:PiaA protein, Dictyostelium; D015800:Protozoan Proteins; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases; D006152:Cyclic GMP