Direct observation of folded human telomeric i-motif at neutral pH by single-molecule FRET

Abstract

i-Motifs are four stranded DNA structures comprised of parallel-stranded DNA duplexes connected in an anti-parallel orientation by intercalated, cytosine-cytosine base pairs. They are stabilised under acidic conditions by C-C base pairing formed via hemi-protonation of the N3; folding is rapid and this property has been utilised in many nanotechnological applications. Sequences which fold into i-motifs are also prevalent across the human genome and are enriched in regions related to control of gene expression.