Mir B, Serrano I, Buitrago D, Orozco M, Escaja N, Gonzalez C.
J Am Chem Soc 2017 Oct; 139: 13985.
e report here the solution structure of several repetitive DNA sequences containing d(TCGTTCCGT) and related repeats. At physiological pH, these sequences fold into i-motif like quadruplexes in which every two repeats a globular structure is stabilized by two hemiprotonated C:C+ base pairs, flanked by two minor groove tetrads resulting from the association of G:C or G:T base pairs. The interaction between the minor groove tetrads and the nearby C:C+ base pairs affords a strong stabilization, which results in effective pHT values above 7.5. Longer sequences with more than two repeats are able to fold in tandem, forming a rosary bead-like structure. Bioinformatics analysis shows that these sequences are prevalent in the human genome, and are present in development-related genes.
PubMed: 28933543. Doi: 10.1021/jacs.7b07383.