PBX PROTEINS DISPLAY HEXAPEPTIDE-DEPENDENT COOPERATIVE DNA-BINDING WITH A SUBSET OF HOX PROTEINS
PBX PROTEINS DISPLAY HEXAPEPTIDE-DEPENDENT COOPERATIVE DNA-BINDING WITH A SUBSET OF HOX PROTEINS
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DOI：
10.1101/gad.9.6.663
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发表时间：
1995-03-15
影响因子：
10.5
通讯作者：
CLEARY, ML
中科院分区：
文献类型：
--
作者：
CHANG, CP;SHEN, WF;CLEARY, ML
人原癌基因PBX 1编码果蝇外齿同源物，一种调节选择HOM蛋白的发育和DNA结合特异性的趋异同源结构域蛋白。我们证明了野生型Pbx蛋白和嵌合E2 a-Pbx 1癌蛋白与HoxB 4，B6和B7的Hox/HOM蛋白类的HoxB 4，B6和B7的共识DNA探针合作结合。Hox-Pbx相互作用的特异性由Pbx蛋白不能与HoxA 10或果蝇甚至跳过的合成DNA靶点协同结合而提出。定点突变表明，Hox同源结构域上游的六肽基序（IYPWMK）是HoxB 6和B7与Pbx蛋白协同结合DNA所必需的。HoxB 7六肽到HoxA 10上的植入赋予其强大的合作性质，表明高度保守的六肽元件作为界定Hox-Pbx协同性的分子决定因素之一的功能作用。Pbx同源结构域是必要的，但不是足够的协同性，这需要保守的同源结构域的羧基端的氨基酸。这些研究结果表明，Hox和Pbx蛋白之间的相互作用调节其DNA结合特性，这表明Pbx和Hox蛋白作为异型复合物平行作用，以调节特定的从属基因的表达。
The human proto-oncogene PBX1 codes for a homolog of Drosophila extradenticle, a divergent homeo domain protein that modulates the developmental and DNA-binding specificity of select HOM proteins. We demonstrate that wild-type Pbx proteins and chimeric E2a-Pbx1 oncoproteins cooperatively bind a consensus DNA probe with HoxB4, B6, and B7 of the Antennapedia class of Hox/HOM proteins. Specificity of Hox-Pbx interactions was suggested by the inability of Pbx proteins to cooperatively bind the synthetic DNA target with HoxA10 or Drosophila even-skipped. Site-directed mutagenesis showed that the hexapeptide motif (IYPWMK) upstream of the Hox homeo domain was essential for HoxB6 and B7 to cooperatively bind DNA with Pbx proteins. Engraftment of the HoxB7 hexapeptide onto HoxA10 endowed it with robust cooperative properties, demonstrating a functional role for the highly conserved hexapeptide element as one of the molecular determinants delimiting Hox-Pbx cooperativity. The Pbx homeo domain was necessary but not sufficient for cooperativity, which required conserved amino acids carboxy-terminal of the homeo domain. These findings demonstrate that interactions between Hox and Pbx proteins modulate their DNA-binding properties, suggesting that Pbx and Hox proteins act in parallel as heterotypic complexes to regulate expression of specific subordinate genes.