Evidence that a combined activator-repressor protein regulates Dictyostelium stalk cell differentiation.
The ecmA gene is expressed in Dictyostelium prestalk cells and is inducible by differentiation-inducing factor (DIF), a low-molecular-weight lipophilic substance. The ecmB gene is expressed in stalk cells and is under negative control by two repressor elements. Each repressor element contains two copies of the sequence TTGA in an inverted relative orientation. There are activator elements in the ecmA promoter that also contain two TTGA sequences, but in the same relative orientation. Gel retardation assays suggest that the same protein binds to the ecmB repressor and the ecmA activator. We propose that DIF induces prestalk cell differentiation by activating this protein and that the protein also binds to the promoters of stalk-specific genes, acting as a repressor that holds cells in the prestalk state until culmination is triggered.
Kawata
T
T
MRC Laboratory of Molecular Cell Biology, University College Lodon, KUK.
Early
A
A
Williams
J
J
D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation / Q000235:genetics*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004271:DNA, Fungal; D004268:DNA-Binding Proteins / Q000502:physiology; D004023:Dictyostelium / Q000166:cytology* / Q000235:genetics; D004789:Enzyme Activation; D016326:Extracellular Matrix Proteins / Q000235:genetics*; D005656:Fungal Proteins / Q000235:genetics; D005786:Gene Expression Regulation; D006588:Hexanones / Q000378:metabolism*; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D015800:Protozoan Proteins; D012045:Regulatory Sequences, Nucleic Acid; D015398:Signal Transduction
D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D016326:Extracellular Matrix Proteins; D005656:Fungal Proteins; D006588:Hexanones; D015800:Protozoan Proteins; C069214:ecmB protein, Dictyostelium; D017868:Cyclic AMP-Dependent Protein Kinases