DSSR-PyMOL cartoon-block schematics: PDB entry 1ql5

PDB-id

1ql5; DSSR-derived features in text and JSON formats

Class

DNA

Method

NMR

Summary

DNA decamer duplex containing t5-t6 photoadduct

Reference

Lee J-H, Choi Y-J, Choi B-S (2000): "Solution Structure of a DNA Decamer Duplex Containing the 3' T.T Base Pair of the Cis-Syn Cyclobutane Pyrimidine Dimer: Implication for the Mutagenic Property of the Cis-Syn Dimer." Nucleic Acids Res., 28, 1794. doi: 10.1093/NAR/28.8.1794.

Abstract

The cis - syn dimer is the major DNA photoproduct produced by UV irradiation. In order to determine the origin of the mutagenic property of the cis - syn dimer, we used NMR restraints and molecular dynamics to determine the solution structure of a DNA decamer duplex containing a wobble pair between the 3'-T of the cis - syn dimer and the opposite T residue (CS/TA duplex). The solution structure of the CS/TA duplex revealed that the 3'-T x T base pair of the cis - syn dimer had base pair geometry that was significantly different from the canonical Watson-Crick base pair and caused destabilization and conformational distortion of its 3'-region. However, a 3'-T x A base pair at the cis - syn dimer within this related DNA decamer maintains the normal Watson-Crick base pair geometry and causes little distortion in the conformation of its 3'-side. Our results show that in spite of its stable hydrogen bonding, the insertion of a T residue opposite the 3'-T of the cis - syn dimer is inhibited by structural distortion caused by the 3'-T x T base pair. This may explain why the frequency of the 3'-T-->A transversion, which is the major mutation produced by the cis - syn dimer, is only 4%.