Abstract
We have determined the three-dimensional (3D) structure of DNA duplex that includes tandem HgII-mediated T–T base pairs (thymine–HgII–thymine, T–HgII–T) with NMR spectroscopy in solution. This is the first 3D structure of metallo-DNA (covalently metallated DNA) composed exclusively of ‘NATURAL’ bases. The T–HgII–T base pairs whose chemical structure was determined with the 15N NMR spectroscopy were well accommodated in a B-form double helix, mimicking normal Watson–Crick base pairs. The Hg atoms aligned along DNA helical axis were shielded from the bulk water. The complete dehydration of Hg atoms inside DNA explained the positive reaction entropy (ΔS) for the T–HgII–T base pair formation. The positive ΔS value arises owing to the HgII dehydration, which was approved with the 3D structure. The 3D structure explained extraordinary affinity of thymine towards HgII and revealed arrangement of T–HgII–T base pairs in metallo-DNA.
Highlights
The positive ÁS recorded for T–HgII–T base pair formation with isothermal titration calorimetry (ITC) [24] indicated its peculiarity, since biomolecular complexations are usually linked with negative ÁS values [26,27]
We studied the effects of T–HgII–T nearest neighbour base pairs on thermal stabilities (Tm) value (Supplementary Figure S1) and the highest stability was observed for the closely related sequence with the HgII-bound DNA duplex 12
The first 3D structure of metallo-DNA composed exclusively of ‘NATURAL’ bases and containing tandem T–HgII–T base pairs was determined in solution
Summary
The metal-mediated base pairs (the metallo base pairs) are currently being explored toward genetic code expansion [1,2,3,4], development of metallo-DNAs [5,6,7,8,9,10,11,12], molecular magnets [13,14], electric nano-wires [15,16,17,18,19] and metal ion-sensors [20,21]. The HgII-sensor employing thymine–HgII–thymine (T–HgII–T) base pair was the first successful application [20]. The success of this HgII-sensor was owing to both the extraordinary HgII-thymine specificity and the thermal stability of T–HgII–T base pair [22,23,24,25]. The thermal stability of the T–HgII–T base pair was similar as those of normal Watson–Crick (W–C) base pairs [24]. The lack of structural data for T–HgII–T base pairs in a DNA duplex prohibited rational explanation of this positive ÁS. The elucidation of entropic contributors from three-dimensional yThese authors contributed to the paper as first authors
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
