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oai:recercat.cat:2445/1935842025-12-04T19:32:58Zcom_2072_1057col_2072_478908col_2072_478917

pH-Dependent Capping Interactions Induce Large-Scale Structural Transitions in i-Motifs Serrano Chacón, Israel Mir, Bartomeu Cupellini, Lorenzo Colizzi, Francesco Orozco López, Modesto Escaja Sánchez, Núria González, Carlos Oligonucleòtids Àcids nucleics ADN Oligonucleotides Nucleic acids DNA We study here a DNA oligonucleotide having the ability to form two different i-motif structures whose relative stability depends on pH and temperature. The major species at neutral pH is stabilized by two C:C+ base pairs capped by two minor groove G:C:G:C tetrads. The high pH and thermal stability of this structure are mainly due to the favorable effect of the minor groove tetrads on their adjacent positively charged C:C+ base pairs. At pH 5, we observe a more elongated i-motif structure consisting of four C:C+ base pairs capped by two G:T:G:T tetrads. Molecular dynamics calculations show that the conformational transition between the two structures is driven by the protonation state of key cytosines. In spite of large conformational differences, the transition between the acidic and neutral structures can occur without unfolding of the i-motif. These results represent the first case of a conformational switch between two different i-motif structures and illustrate the dramatic pH-dependent plasticity of this fascinating DNA motif. 2023-02-14T10:30:51Z 2023-02-14T10:30:51Z 2023-02-06 2023-02-08T08:30:20Z info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 1520-5126 https://hdl.handle.net/2445/193584 6575489 36745195 eng Reproducció del document publicat a: https://doi.org/10.1021/jacs.2c13043 Journal of the American Chemical Society, 2023, vol. 145, num. 6, p. 3696–3705 https://doi.org/10.1021/jacs.2c13043 cc by (c) Serrano Chacón, Israel et al., 2023 http://creativecommons.org/licenses/by/3.0/es/ info:eu-repo/semantics/openAccess 10 p. application/pdf ACS Publications Articles publicats en revistes (Institut de Recerca Biomèdica (IRB Barcelona))