Evolutionarily conserved domains required for activation and repression functions of the Drosophila Hox protein Ultrabithorax.
While testing the functions of deletion mutants in the Hox protein Ultrabithorax (Ubx), we found that the embryonic repression function of Ubx on Distal-less transcription in limb primordia is highly concentration dependent. The steep sigmoidal relationship between in vivo Ubx concentration and Distal-less repression is dependent on the Ubx YPWM motif. This suggests that Ubx cooperatively assembles a multi-protein repression complex on Distal-less regulatory DNA with the YPWM motif as a key protein-protein interface in this complex. Our deletion mutants also provide evidence for a transcriptional activation domain in the N-terminal 19 amino acids of Ubx. This proposed activation domain contains a variant of the SSYF motif that is found at the N termini of many Hox proteins, and is conserved in the activation domain of another Hox protein, Sex combs reduced. These results suggest that the N-terminal region containing the SSYF motif has been conserved in many Hox proteins for its role in transcriptional activation.
Tour
Ella
E
Section in Cell and Developmental Biology, Division of Biology, University of California, San Diego, La Jolla, CA 92093, USA.
Hittinger
Chris Todd
CT
McGinnis
William
W
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D017124:Conserved Sequence / Q000502:physiology*; D029721:Drosophila Proteins / Q000235:genetics / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D018398:Homeodomain Proteins / Q000235:genetics / Q000502:physiology*; D046912:Multiprotein Complexes; D009154:Mutation; D012097:Repressor Proteins; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D014158:Transcription, Genetic; D015533:Transcriptional Activation
D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D046912:Multiprotein Complexes; D012097:Repressor Proteins; D014157:Transcription Factors; C066177:Ubx protein, Drosophila