The dynamic character of the G-quadruplex element in the c-MYC promoter and modification by TMPyP4

J Am Chem Soc. 2004 Jul 21;126(28):8702-9. doi: 10.1021/ja040022b.


The nuclease hypersensitivity element III1 (NHE III1) upstream of the P1 and P2 promoters of c-MYC controls 80-90% of the transcriptional activity of this gene. The purine-rich strand in this region can form a G-quadruplex structure that is a critical part of the silencer element for this promoter. We have demonstrated that this G-quadruplex structure can form a mixture of four biologically relevant parallel-loop isomers, which upon interaction with the cationic porphyrin TMPyP4 are converted to mixed parallel/antiparallel G-quadruplex structures.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • DNA / chemistry
  • DNA / drug effects
  • DNA / genetics
  • Genes, myc / drug effects
  • Genes, myc / genetics*
  • Humans
  • Models, Genetic
  • Nucleic Acid Conformation / drug effects
  • Porphyrins / pharmacology*
  • Promoter Regions, Genetic / drug effects
  • Promoter Regions, Genetic / genetics*
  • Silencer Elements, Transcriptional / drug effects*
  • Silencer Elements, Transcriptional / genetics
  • Transcription, Genetic / genetics*


  • Porphyrins
  • tetra(4-N-methylpyridyl)porphine
  • DNA