The hexapeptide LFPWMR in Hoxb-8 is required for cooperative DNA binding with Pbx1 and Pbx2 proteins.
The Hox gene products are DNA-binding proteins, containing a homeodomain, which function as a class of master control proteins establishing the body plan in organisms as diverse as Drosophila and vertebrates. Hox proteins have recently been shown to bind cooperatively to DNA with another class of homeodomain proteins that include extradenticle, Pbx1, and Pbx2. Hox gene products contain a highly conserved hexapeptide connected by a linker of variable length to the homeodomain. We show that the hexapeptide and the linker region are required for cooperativity with Pbx1 and Pbx2 proteins. Many of the conserved residues present in the Hoxb-8 hexapeptide are required to modulate the DNA binding of the Pbx proteins. Position of the hexapeptide relative to the homeodomain is important. Although deletions of two and four residues of the linker peptide still show cooperative DNA binding, removal of all six linker residues strongly reduces cooperativity. In addition, an insertion of 10 residues within the linker peptide significantly lowers cooperative DNA binding. These results show that the hexapeptide and the position of the hexapeptide relative to the homeodomain are important determinants to allow cooperative DNA binding involving Hox and Pbx gene products.
Neuteboom
S T
ST
Department of Biology, University of California at San Diego, La Jolla 92093, USA.
Peltenburg
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LT
van Dijk
M A
MA
Murre
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C
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism; D005801:Genes, Homeobox; D018398:Homeodomain Proteins / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D016296:Mutagenesis; D015345:Oligonucleotide Probes; D009842:Oligopeptides; D016133:Polymerase Chain Reaction; D000075062:Pre-B-Cell Leukemia Transcription Factor 1; D011518:Proto-Oncogene Proteins / Q000737:chemistry / Q000378:metabolism*; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D014714:Vertebrates; D014982:Xenopus laevis
D017931:DNA Primers; D004268:DNA-Binding Proteins; C490669:HOXB8 protein, human; D018398:Homeodomain Proteins; C095822:Hoxb8 protein, mouse; D015345:Oligonucleotide Probes; D009842:Oligopeptides; C090465:PBX2 protein, human; C490382:Pbx2 protein, mouse; D000075062:Pre-B-Cell Leukemia Transcription Factor 1; D011518:Proto-Oncogene Proteins; C083400:PBX1 protein, human