Crystal Structure of Metallo DNA Duplex Containing Consecutive Watson-Crick-like T-Hg~II-T Base Pairs

摘要

The metallo DNA duplex containing mercury-mediated T-T base pairs is an attractive biomacromolecular nanomaterial which can be applied to nanodevices such as ion sensors. Reported herein is the first crystal structure of a B-form DNA duplex containing two consecutive T-Hg~(II)-T base pairs. The Hg~(II) ion occupies the center between two T residues. The N3-Hg~(II) bond distance is 2.0 A. The relatively short Hg"-Hg" distance (3.3 A) observed in consecutive T-Hg"-T base pairs suggests that the metallophilic attraction could exist between them and may stabilize the B-form double helix. To support this, the DNA duplex is largely distorted and adopts an unusual nonhelical conformation in the absence of Hg~(II). The structure of the metallo DNA duplex itself and the Hg~(II)-induced structural switching from the nonhelical form to the B-form provide the basis for structure-based design of metal-conjugated nucleic acid nanomaterials.