Characterization of a dimerization motif in AP-2 and its function in heterologous DNA-binding proteins.
The mammalian transcription factor AP-2 is a retinoic acid inducible sequence-specific DNA-binding protein that is developmentally regulated. In this report, the functional domains necessary for AP-2 DNA binding were studied. AP-2 required a dimerization domain and an adjacent region of net basic charge to achieve a sequence-specific protein:DNA interaction. The sequences responsible for dimerization consisted of two putative amphipathic alpha helices separated by a large intervening span region. This helix-span-helix (HSH) domain was unable to bind DNA when separated from the basic region, but was still capable of dimerization. The ability of the HSH domain to function as a module that promotes DNA binding through dimerization was further demonstrated by attaching it to the heterologous basic region of the c-Jun proto-oncogene product. The resulting chimeric protein specifically recognized an AP-1 DNA-binding site in the absence of an intact c-Jun leucine repeat and in a manner that was dependent on the presence of a functional AP-2 dimerization domain.
Williams
T
T
Howard Hughes Medical Institute, Department of Molecular and Cell Biology, University of California, Berkeley 94720.
Tjian
R
R
D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D004247:DNA / Q000378:metabolism*; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D013329:Structure-Activity Relationship; D050656:Transcription Factor AP-2; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*
D004268:DNA-Binding Proteins; D046911:Macromolecular Substances; D011993:Recombinant Fusion Proteins; D050656:Transcription Factor AP-2; D014157:Transcription Factors; D000255:Adenosine Triphosphate; D004247:DNA