LexA chimeras reveal the function of Drosophila Fos as a context-dependent transcriptional activator.
The transcriptional activation potential of proteins can be assayed in chimeras containing a heterologous DNA-binding domain that mediates their recruitment to reporter genes. This approach has been widely used in yeast and in transient mammalian cell assays. Here, we applied it to assay the transactivation potential of proteins in transgenic Drosophila embryos. We found that a chimera between the DNA-binding bacterial LexA protein and the transactivation domain from yeast GAL4 behaved as a potent synthetic activator in all embryonic tissues. In contrast, a LexA chimera containing Drosophila Fos (Dfos) required an unexpected degree of context to function as a transcriptional activator. We provide evidence to suggest that this context is provided by Djun and Mad (a Drosophila Smad), and that these partner factors need to be activated by signaling from Jun N-terminal kinase and decapentaplegic, respectively. Because Dfos behaves as an autonomous transcriptional activator in more artificial assays systems, our data suggest that context-dependence of transcription factors may be more prevalent than previously thought.
Szüts
D
D
Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, United Kingdom.
Bienz
M
M
D000818:Animals; D030801:Animals, Genetically Modified; D001426:Bacterial Proteins / Q000378:metabolism*; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000235:genetics*; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000196:embryology / Q000235:genetics*; D004625:Embryo, Nonmammalian / Q000502:physiology; D004742:Enhancer Elements, Genetic; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics*; D019476:Insect Proteins / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D012697:Serine Endopeptidases / Q000378:metabolism*; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation; D000099160:LexA Repressor Protein
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D005656:Fungal Proteins; D018398:Homeodomain Proteins; D019476:Insect Proteins; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D016760:Proto-Oncogene Proteins c-fos; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D012697:Serine Endopeptidases; D014157:Transcription Factors; D000099160:LexA Repressor Protein; C052130:GAL4 protein, S cerevisiae; C066177:Ubx protein, Drosophila; C064196:dpp protein, Drosophila