I-motif DNA structures are formed in the nuclei of human cells

Nat Chem. 2018 Jun;10(6):631-637. doi: 10.1038/s41557-018-0046-3. Epub 2018 Apr 23.


Human genome function is underpinned by the primary storage of genetic information in canonical B-form DNA, with a second layer of DNA structure providing regulatory control. I-motif structures are thought to form in cytosine-rich regions of the genome and to have regulatory functions; however, in vivo evidence for the existence of such structures has so far remained elusive. Here we report the generation and characterization of an antibody fragment (iMab) that recognizes i-motif structures with high selectivity and affinity, enabling the detection of i-motifs in the nuclei of human cells. We demonstrate that the in vivo formation of such structures is cell-cycle and pH dependent. Furthermore, we provide evidence that i-motif structures are formed in regulatory regions of the human genome, including promoters and telomeric regions. Our results support the notion that i-motif structures provide key regulatory roles in the genome.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Cycle
  • Cell Nucleus / chemistry*
  • DNA / chemistry*
  • DNA / immunology
  • Genome, Human
  • HeLa Cells
  • Humans
  • Hydrogen-Ion Concentration
  • Immunoglobulin Fragments / immunology
  • MCF-7 Cells
  • Nucleic Acid Conformation*
  • Promoter Regions, Genetic
  • Telomere


  • Immunoglobulin Fragments
  • DNA