GBF-dependent family genes morphologically suppress the partially active Dictyostelium STATa strain.
Transcription factor Dd-STATa, a functional Dictyostelium homologue of metazoan signal transducers and activators of transcription proteins, is necessary for culmination during development. We have isolated more than 18 putative multicopy suppressors of Dd-STATa using genetic screening. One was hssA gene, whose expression is known to be G-box-binding-factor-dependent and which was specific to prestalk A (pstA) cells, where Dd-STATa is activated. Also, hssA mRNA was expressed in pstA cells in the Dd-STATa-null mutant. At least 40 hssA-related genes are present in the genome and constitute a multigene family. The tagged HssA protein was translated; hssA encodes an unusually high-glycine-serine-rich small protein (8.37 kDa), which has strong homology to previously reported cyclic-adenosine-monophosphate-inducible 2C and 7E proteins. Overexpression of hssA mRNA as well as frame-shifted versions of hssA RNA suppressed the phenotype of the partially active Dd-STATa strain, suggesting that translation is not necessary for suppression. Although overexpression of prespore-specific genes among the family did not suppress the parental phenotype, prestalk-specific family members did. Although overexpression of the hssA did not revert the expression of Dd-STATa target genes, and although its suppression mechanism remains unknown, morphological reversion implies functional relationships between Dd-STATa and hssA.
Shimada
Nao
N
Department of Biology, Faculty of Science, Toho University, 2-2-1 Miyama, Funabashi, Chiba, 274-8510, Japan.
Kanno-Tanabe
Naoko
N
Minemura
Kakeru
K
Kawata
Takefumi
T
D000818:Animals; D004023:Dictyostelium / Q000145:classification / Q000235:genetics*; D051790:G-Box Binding Factors / Q000235:genetics; D005786:Gene Expression Regulation; D017125:Genes, Protozoan; D016153:Genes, Suppressor; D008957:Models, Genetic; D010802:Phylogeny; D015800:Protozoan Proteins / Q000235:genetics* / Q000378:metabolism; D050791:STAT Transcription Factors / Q000235:genetics* / Q000378:metabolism
D051790:G-Box Binding Factors; D015800:Protozoan Proteins; D050791:STAT Transcription Factors; C426583:STATa protein, Dictyostelium