I-MOTIF DNA: SIGNIFICANCE AND FUTURE PROSPECTIVE

Since the first report of its existence emerged in the early 1990s, i-motif DNA has gained much interest among the other non-canonical DNA structures in recent years. It is a quadruplex structure made up of two parallel duplexes formed by folding of cytosine-rich sequences of the nucleic acid with the cytosine•cytosine+ base pair as its building block. Earlier known to exist only at acidic pH, genomic sequences that form stable i-motif structures even at neutral pH under certain conditions have been reported recently. It is visible during G1 stage of cell cycle and is also seen in promoter sites and in telomeres. It is the only known nucleic acid structure involving systematic base intercalation. Owing to its sharp, fast and reversible pH-driven conformational changes it has already inspired the designs of various nanomachines and has got wide applicability in fields of nanotechnology and analytical chemistry. Its recent confirmation in vivo has given insight to its potential role in various important biological processes like replication, regulation of oncogene expression, and telomere functions. Therefore, the targeting of i-motif DNA and active search for appropriate ligands interacting with this non-canonical structure is an emerging area of research in medicinal and nucleic acid chemistry