Activation and repression by the C-terminal domain of Dorsal.
In the Drosophila embryo, Dorsal, a maternally expressed Rel family transcription factor, regulates dorsoventral pattern formation by activating and repressing zygotically active fate-determining genes. Dorsal is distributed in a ventral-to-dorsal nuclear concentration gradient in the embryo, the formation of which depends upon the spatially regulated inhibition of Dorsal nuclear uptake by Cactus. Using maternally expressed Gal4/Dorsal fusion proteins, we have explored the mechanism of activation and repression by Dorsal. We find that a fusion protein containing the Gal4 DNA-binding domain fused to full-length Dorsal is distributed in a nuclear concentration gradient that is similar to that of endogenous Dorsal, despite the presence of a constitutively active nuclear localization signal in the Gal4 domain. Whether this fusion protein activates or represses reporter genes depends upon the context of the Gal4-binding sites in the reporter. A Gal4/Dorsal fusion protein lacking the conserved Rel homology domain of Dorsal, but containing the non-conserved C-terminal domain also mediates both activation and repression, depending upon Gal4-binding site context. A region close to the C-terminal end of the C-terminal domain has homology to a repression motif in Engrailed - the eh1 motif. Deletion analysis indicates that this region mediates transcriptional repression and binding to Groucho, a co-repressor known to be required for Dorsal-mediated repression. As has previously been shown for repression by Dorsal, we find that activation by Dorsal, in particular by the C-terminal domain, is modulated by the maternal terminal pattern-forming system.
Flores-Saaib
R D
RD
Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095-1569, USA.
Jia
S
S
Courey
A J
AJ
D020816:Amino Acid Motifs; D000818:Animals; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins; D001665:Binding Sites; D019521:Body Patterning; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D004268:DNA-Binding Proteins / Q000378:metabolism; D004330:Drosophila / Q000196:embryology* / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins; D005260:Female; D017344:Genes, Insect; D009687:Nuclear Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D010750:Phosphoproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D014157:Transcription Factors; D014158:Transcription, Genetic
D051792:Basic Helix-Loop-Helix Proteins; D017931:DNA Primers; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D009687:Nuclear Proteins; D010750:Phosphoproteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C062236:dl protein, Drosophila; C091023:gro protein, Drosophila