Myc/Max and other helix-loop-helix/leucine zipper proteins bend DNA toward the minor groove.
A distinct family of DNA-binding proteins is characterized by the presence of adjacent "basic," helix-loop-helix, and leucine zipper domains. Members of this family include the Myc oncoproteins, their binding partner Max, and the mammalian transcription factors USF, TFE3, and TFEB. Consistent with their homologous domains, these proteins bind to DNA containing the same core hexanucleotide sequence CACGTG. Analysis of the conformation of DNA in protein-DNA complexes has been undertaken with a circular permutation assay. Large mobility anomalies were detected for all basic/helix-loop-helix/leucine zipper proteins tested, suggesting that each protein induced a similar degree of bending. Phasing analysis revealed that basic/helix-loop-helix/leucine zipper proteins orient the DNA bend toward the minor groove. The presence of in-phase spacing between adjacent binding sites for this family of proteins in the immunoglobulin heavy-chain enhancer suggests the possible formation of an unusual triple-bended structure and may have implications for the activities of Myc.
Fisher
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Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
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Sharp
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D001483:Base Sequence; D050976:Basic-Leucine Zipper Transcription Factors; D001665:Binding Sites; D004247:DNA / Q000648:ultrastructure*; D004268:DNA-Binding Proteins / Q000737:chemistry*; D066298:In Vitro Techniques; D016350:Leucine Zippers; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D016271:Proto-Oncogene Proteins c-myc / Q000737:chemistry*; D014157:Transcription Factors / Q000737:chemistry*
D050976:Basic-Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; D046911:Macromolecular Substances; C067850:Myc associated factor X; D009838:Oligodeoxyribonucleotides; D016271:Proto-Oncogene Proteins c-myc; D014157:Transcription Factors; D004247:DNA