Functional interaction of the c-Myc transactivation domain with the TATA binding protein: evidence for an induced fit model of transactivation domain folding

Biochemistry. 1996 Jul 23;35(29):9584-93. doi: 10.1021/bi960793v.


c-Myc is a member of a family of sequence specific-DNA binding proteins that are thought to regulate the transcription of genes involved in normal cell growth, differentiation, and apoptosis. In order to understand how human c-myc functions as a transcription factor, we have studied the mechanism of action and structure of the N-terminal transactivation domain, amino acids 1-143. In a protein interaction assay, c-myc1-143 bound selectively to two basal transcription factors, the TATA binding protein (TBP) and the RAP74 subunit of TFIIF. Furthermore, the isolated c-myc transactivation domain competed for limiting factors required for the assembly of a functional preinitiation complex. This squelching of basal transcription was reversed in a dose-dependent manner by recombinant TBP. Taken together, these results identify TBP as an important target for the c-myc transactivation domain, during transcriptional initiation. Similar to other transactivation domains, the c-myc1-143 polypeptide showed little or no evidence of secondary structure, when measured by circular dichroism spectroscopy (CD) in aqueous solution. However, significant alpha-helical conformation was observed in the presence of the hydrophobic solvent trifluoroethanol. Strikingly, addition of TBP caused changes in the CD spectra consistent with induction of protein conformation in c-myc1-143 during interaction with the target factor. This change was specific for TBP as a similar effect was not observed in the presence of TFIIB. These data support a model in which target factors induce or stabilize a structural conformation in activator proteins during transcriptional transactivation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / metabolism
  • Base Sequence
  • Circular Dichroism
  • DNA Primers
  • DNA-Binding Proteins / metabolism*
  • Humans
  • Molecular Sequence Data
  • Peptide Fragments / chemistry
  • Peptide Fragments / metabolism
  • Protein Conformation
  • Protein Folding
  • Protein Structure, Secondary
  • Proto-Oncogene Proteins c-myc / chemistry*
  • Proto-Oncogene Proteins c-myc / metabolism
  • Recombinant Fusion Proteins / metabolism
  • Repressor Proteins / metabolism
  • Serine Endopeptidases / metabolism
  • TATA Box
  • TATA-Box Binding Protein
  • Transcription Factors / metabolism*
  • Transcription Factors, TFII*
  • Transcription, Genetic
  • Transcriptional Activation*


  • Bacterial Proteins
  • DNA Primers
  • DNA-Binding Proteins
  • LexA protein, Bacteria
  • Peptide Fragments
  • Proto-Oncogene Proteins c-myc
  • Recombinant Fusion Proteins
  • Repressor Proteins
  • TATA-Box Binding Protein
  • Transcription Factors
  • Transcription Factors, TFII
  • Serine Endopeptidases
  • transcription factor TFIIF