title: DNA binding of Myc/Max/Mad network complexes to oligonucleotides containing two E box elements: c-Myc/Max heterodimers do not bind DNA cooperatively.
abstract: Myc proteins function in heterodimeric complexes with Max proteins as transcriptional regulators at least in part by binding to E box sequences with a 5'-CACGTG core. Since such E boxes are found frequently in the human genome and since other proteins besides Myc/Max can bind to similar or identical sequences it is unclear how the specificity of E box-mediated gene transcription is determined. Recent findings were interpreted to suggest that Myc/Max, but not Max/Max or USF complexes, bind cooperatively to DNA sequences that contain two E box elements. This provides a potential mechanism for selective E box-mediated gene transcription. To extend this finding we analyzed DNA binding of c-Myc/Max complexes using a transient COS-7 expression system. In both competition and titration experiments no cooperative binding of c-Myc/Max heterodimers to probes with two E boxes was observed. Furthermore, c-Myc-specific transcription of reporter gene constructs did not reveal cooperativity. Thus ourfindings argue against cooperative DNA binding of Myc proteins as a selection mechanism for E box-dependent transcription.
authors.affiliation: Institut für Molekularbiologie, Medizinische Hochschule Hannover, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Vervoorts
authors.forename: B
authors.initials: B
authors.lastname: Lüscher
mesh_terms: D000818:Animals; D001483:Base Sequence; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D050976:Basic-Leucine Zipper Transcription Factors; D019556:COS Cells; D004247:DNA / Q000378:metabolism*; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000378:metabolism*; D019281:Dimerization; D006801:Humans; D011485:Protein Binding; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism*; D012097:Repressor Proteins; D014157:Transcription Factors; D014158:Transcription, Genetic
chemical_list: D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D050976:Basic-Leucine Zipper Transcription Factors; D017931:DNA Primers; D004268:DNA-Binding Proteins; C499330:MAX protein, human; C079439:MXD1 protein, human; C067850:Myc associated factor X; D016271:Proto-Oncogene Proteins c-myc; D012097:Repressor Proteins; D014157:Transcription Factors; D004247:DNA