Dimerization and DNA binding facilitate alpha-helix formation of Max in solution

J Biochem. 1997 Oct;122(4):711-6. doi: 10.1093/oxfordjournals.jbchem.a021813.


Max is a basic region/helix-loop-helix/leucine zipper (b/HLH/Z) protein that forms a hetero-complex with the Myc family proteins Myc, Mad, and Mxi1, and a homo-complex with itself. These complexes specifically bind to double-stranded DNA containing CACGTG sequences. Here, we report on the structural properties in aqueous solution of a 109-amino-acid protein, Max110, corresponding to the N-terminal domain of Max containing the b/HLH/Z motif (residues 2-110), as characterized by combined use of circular dichroism (CD) and sedimentation equilibrium experiments. The results showed that the alpha-helical content of Max110 increases with increasing protein concentration. The sedimentation equilibrium data indicated that Max110 exists as a monomer at low protein concentration, and forms a dimer at high protein concentration. Further increases in the alpha-helical content of Max110 occur upon addition of DNA with the CACGTG recognition sequence. Thus, dimerization and binding to DNA of Max both favor an increase of the alpha-helical content.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Basic-Leucine Zipper Transcription Factors
  • Circular Dichroism
  • DNA / metabolism*
  • DNA-Binding Proteins / chemistry*
  • DNA-Binding Proteins / metabolism
  • Dimerization
  • Helix-Loop-Helix Motifs
  • Molecular Sequence Data
  • Protein Conformation
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / metabolism
  • Solutions
  • Transcription Factors*


  • Basic-Leucine Zipper Transcription Factors
  • DNA-Binding Proteins
  • Myc associated factor X
  • Recombinant Proteins
  • Solutions
  • Transcription Factors
  • DNA