Concerted dynamics of metallo-base pairs in an A/B-form helical transition.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 31645548.
- Also identified by DOI 10.1038/s41467-019-12440-x and PMC identifier 6811676.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Metal-mediated base pairs expand the repertoire of nucleic acid structures and dynamics. Here we report solution structures and dynamics of duplex DNA containing two all-natural C-Hg<sup>II</sup>-T metallo base pairs separated by six canonical base pairs. NMR experiments reveal a 3:1 ratio of well-resolved structures in dynamic equilibrium. The major species contains two (N3)T-Hg<sup>II</sup>-(N3)C base pairs in a predominantly B-form helix. The minor species contains (N3)T-Hg<sup>II</sup>-(N4)C base pairs and greater A-form characteristics. Ten-fold different <sup>1</sup>J coupling constants (<sup>15</sup>N,<sup>199</sup>Hg) are observed for (N3)C-Hg<sup>II</sup> (114 Hz) versus (N4)C-Hg<sup>II</sup> (1052 Hz) connectivities, reflecting differences in cytosine ionization and metal-bonding strengths. Dynamic interconversion between the two types of C-Hg<sup>II</sup>-T base pairs are coupled to a global conformational exchange between the helices. These observations inspired the design of a repetitive DNA sequence capable of undergoing a global B-to-A-form helical transition upon adding Hg<sup>II</sup>, demonstrating that C-Hg<sup>II</sup>-T has unique switching potential in DNA-based materials and devices.
Medical subject headings
- DNA, A-Form
- DNA, B-Form
- Mercury