The DNA binding specificity of Ultrabithorax is modulated by cooperative interactions with extradenticle, another homeoprotein.
The Ultrabithorax (Ubx) and Antennapedia (Antp) genes of Drosophila encode homeodomain proteins that have very similar DNA binding specificities in vitro but specify the development of different segmental patterns in vivo. We describe cooperative interactions between Ubx protein and a divergent homeodomain protein, extradenticle (exd), that selectively increases the affinity of Ubx, but not Antp, for a particular DNA target. We also provide evidence that Ubx and exd bind to neighboring sites on this DNA and interact directly to stabilize the DNA-bound form of Ubx. Thus, the ability of different homeotic genes to specify distinct segmental patterns may depend on cooperative interactions with proteins such as exd that selectively modulate their otherwise similar DNA binding specificities.
Chan
S K
SK
Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York 10032.
Jaffe
L
L
Capovilla
M
M
Botas
J
J
Mann
R S
RS
D000596:Amino Acids / Q000502:physiology; D000818:Animals; D051943:Antennapedia Homeodomain Protein; D001483:Base Sequence; D001665:Binding Sites; D004247:DNA / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004330:Drosophila / Q000378:metabolism; D029721:Drosophila Proteins; D015870:Gene Expression; D005801:Genes, Homeobox / Q000502:physiology; D018398:Homeodomain Proteins; D007301:Insect Hormones / Q000235:genetics; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*
D000596:Amino Acids; D051943:Antennapedia Homeodomain Protein; C497974:Antp protein, Drosophila; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D007301:Insect Hormones; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C066177:Ubx protein, Drosophila; C064196:dpp protein, Drosophila; C083405:exd protein, Drosophila; D004247:DNA