Structural and thermodynamic studies of a DNA i-motif: Investigating the monomer, dimer, and tetramer human telomere sequence context
MetadataShow full item record
elomeres are protein DNA complexes found at the ends of eukaryotic chromosomes. The human telomere sequence has a G-rich strand, (TTAGGG), complemented to a C-rich strand, (CCCTAA). Previous studies of the G-rich strand indicate that this sequence folds into a distinct conformation, designated as a G quadruplex. The C-rich strand has also been shown to form an unusual structure, under slightly acidic conditions, designated as a DNA i-motif. We are investigating the role of the loops on the structure and stability of the conformations formed from (CCCXXX)4, where X is all permutations of A and/or T. To understand the significance of the presence of the loops, structure and stability will be studied for the dimer and tetramer conformations formed from (CCCTAA)x, where X is either a 1 or a 2. These results indicate that the sequence context and the presence or absence of the loops, influences both the midpoint of the heat induced i-motif to single strand transition (Tm) at pH = 5.0, as well as, the midpoint of the H + induced single strand to i-motif transition (pHmp) at 25 °C.