Download MendeleySite-specific incorporation of a fluorescent nucleobase analog enhances i-motif stability and allows monitoring of i-motif folding inside cells.
Mir, B., Serrano-Chacon, I., Medina, P., Macaluso, V., Terrazas, M., Gandioso, A., Garavis, M., Orozco, M., Escaja, N., Gonzalez, C.(2024) Nucleic Acids Res 52: 3375-3389
- PubMed: 38366792
- DOI: https://doi.org/10.1093/nar/gkae106
- Primary Citation of Related Structures:
8OFC - PubMed Abstract:
The i-motif is an intriguing non-canonical DNA structure, whose role in the cell is still controversial. Development of methods to study i-motif formation under physiological conditions in living cells is necessary to study its potential biological functions. The cytosine analog 1,3-diaza-2-oxophenoxazine (tCO) is a fluorescent nucleobase able to form either hemiprotonated base pairs with cytosine residues, or neutral base pairs with guanines. We show here that when tCO is incorporated in the proximity of a G:C:G:C minor groove tetrad, it induces a strong thermal and pH stabilization, resulting in i-motifs with Tm of 39ºC at neutral pH. The structural determination by NMR methods reveals that the enhanced stability is due to a large stacking interaction between the guanines of the tetrad with the tCO nucleobase, which forms a tCO:C+ in the folded structure at unusually-high pHs, leading to an increased quenching in its fluorescence at neutral conditions. This quenching is much lower when tCO is base-paired to guanines and totally disappears when the oligonucleotide is unfolded. By taking profit of this property, we have been able to monitor i-motif folding in cells.
- Instituto de Química Física 'Blas Cabrera'. CSIC. Serrano 119. 28006 Madrid. Spain.
Organizational Affiliation:
