AI Article Synopsis
- The study examined how 5S-Tg (Tg, Thymine glycol) epimers affect DNA structure using molecular dynamics (MD) simulations and Markov State Models (MSMs).
- The findings indicate that while 5S,6S-Tg has minimal impact on DNA helix stability, the base-flipping barrier for Tg is slightly lower than that for normal thymine.
- Different hydrogen bond configurations were identified for the 5S,6R-Tg adenine pairing, leading to varied energy conformations and signaling potentially distinct mechanisms for DNA repair.
Article Abstract
The static and dynamic structures of DNA duplexes affected by 5S-Tg (Tg, Thymine glycol) epimers were studied using MD simulations and Markov State Models (MSMs) analysis. The results show that the 5S,6S-Tg base caused little perturbation to the helix, and the base-flipping barrier was determined to be 4.4 kcal mol-1 through the use of enhanced sampling meta-eABF calculations, comparable to 5.4 kcal mol-1 of the corresponding thymine flipping. Two conformations with the different hydrogen bond structures between 5S,6R-Tg and A19 were identified in several independent MD trajectories. The 5S,6R-Tg:O6HO6•••N1:A19 hydrogen bond is present in the high-energy conformation displaying a clear helical distortion, and near barrier-free Tg base flipping. The low-energy conformation always maintains Watson-Crick base pairing between 5S,6R-Tg and A19, and 5S-Tg base flipping is accompanied by a small barrier of ca. 2.0 KBT (T = 298 K). The same conformations are observed in the MSMs analysis. Moreover, the transition path and metastable structures of the damaged base flipping are for the first time verified through MSMs analysis. The data clearly show that the epimers have completely different influence on the stability of the DNA duplex, thus implying different enzymatic mechanisms for DNA repair.
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| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9458442 | PMC |
| http://dx.doi.org/10.1093/nar/gkac691 | DOI Listing |
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