title: YelA, a putative Dictyostelium translational regulator, acts as antagonist of DIF-1 signaling to control cell-type proportioning.
abstract: DIF-1 (differentiation-inducing factor1) is a polyketide produced by Dictyostelium prespore cells which induces initially uncommitted cells to differentiate as prestalk cells. Exposure of cells to DIF-1 causes transitory hypo-phosphorylation of seven serine residues in YelA, a protein with a region of strong homology to the MIF4G domain of the eukaryotic initiation factor eIF4G. Based upon its domain architecture, which in one important aspect closely resembles that of Death-Associated Protein 5 (DAP5), we predict a role in stimulating internal ribosome entry-driven mRNA translation. The two paradigmatic DIF-1 inducible genes are ecmA (extracellular matrixA) and ecmB. In support of a YelA function in DIF-1 signaling, a YelA null strain showed greatly increased expression of ecmA and ecmB in response to DIF-1. Also, during normal development in the null strain, expression of the two genes is accelerated. This is particularly evident for ecmB, a marker of stalk tube and supporting structure differentiation. Mutants in DIF-1 bio-synthesis or signaling display a rudimentary or no basal disc and, conversely, YelA null mutants produce fruiting bodies with a highly enlarged basal disc that ectopically expresses a stalk tube-specific marker. Thus YelA acts as an antagonist of DIF-1 signaling, with a consequent effect on cell type proportioning and it is predicted to act as a translational regulator.
authors.affiliation: School of Life Sciences, University of Dundee, Dundee, UK. y.yamada@dundee.ac.uk.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Yamada
authors.forename: Chris
authors.initials: C
authors.lastname: Sugden
authors.forename: Jeffrey G
authors.initials: JG
authors.lastname: Williams
mesh_terms: D004023:Dictyostelium / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D048690:Fruiting Bodies, Fungal / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D006588:Hexanones / Q000494:pharmacology*; D000074041:Microorganisms, Genetically-Modified; D010766:Phosphorylation / Q000187:drug effects; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology*
chemical_list: D006588:Hexanones; D015800:Protozoan Proteins; C108028:YelA protein, Dictyostelium; C053433:1-((3,5-dichloro)-2,6-dihydroxy-4-methoxyphenyl)-1-hexanone