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Updated: May 17, 2026
CD Spectroscopy to Study DNA-Protein Interactions
Published on: February 10, 2022
Early stage intercalation of doxorubicin to DNA fragments observed in molecular dynamics binding simulations
Hongxing Lei1, Xiaofeng Wang, Chun Wu
1CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100029, China. leihx@big.ac.cn
Abstract:
The intercalation mode between doxorubicin (an anticancer drug) and two 6-base-pair DNA model fragments (d(CGATCG)₂ and d(CGTACG)₂) has been well studied by X-ray crystallography and NMR experimental methods. Yet, the detailed intercalation pathway at molecular level remains elusive. In this study, we conducted molecular dynamics binding simulations of these two systems using AMBER DNA (parmbsc0) and drug (GAFF) force fields starting from the unbound state. We observed outside binding (minor groove binding or end-binding) in all six independent binding simulations (three for each DNA fragment), followed by the complete intercalation of a drug molecule in two simulations (one for each DNA fragment). First, our data directly supported that the minor groove binding is the dominant pre-intercalation step. Second, we observed that the opening and flipping of a local base pair (A3-T10 for d(CGATCG)₂ and C1-G12 for d(CGTACG)₂) in the two intercalation trajectories. This locally cooperative flipping-intercalation mechanism was different from the previously proposed rise-insertion mechanism by which the distance between two neighboring intact base pairs increases to create a space for the drug insertion. Third, our simulations provided the first set of data to support the applicability of the AMBER DNA and drug force fields in drug-DNA atomistic binding simulations. Implications on the kinetics pathway and drug action are also discussed.
Insights
Molecular dynamics simulations reveal doxorubicin (anticancer drug) primarily binds to DNA minor grooves before intercalation. This study uncovers a novel base-pair flipping mechanism for drug insertion, differing from prior models.
Area of Science:
- Computational Chemistry
- Molecular Biophysics
- Pharmacology
Background:
- Doxorubicin intercalation into DNA is a key anticancer mechanism.
- Previous studies using X-ray crystallography and NMR elucidated binding modes but lacked detailed pathway insights.
- The precise molecular-level intercalation pathway of doxorubicin into DNA remains incompletely understood.
Purpose of the Study:
- To elucidate the molecular-level intercalation pathway of doxorubicin into DNA model fragments.
- To investigate the role of minor groove binding as a pre-intercalation step.
- To validate the use of AMBER DNA and drug force fields for atomistic drug-DNA binding simulations.
Main Methods:
- Conducted molecular dynamics (MD) binding simulations of doxorubicin with two DNA model fragments: d(CGATCG)₂ and d(CGTACG)₂.
- Utilized AMBER DNA (parmbsc0) and drug (GAFF) force fields, initiating simulations from the unbound state.
- Performed six independent simulations (three per DNA fragment) to capture diverse binding events.
Main Results:
- Observed initial outside binding (minor groove or end-binding) in all simulations.
- Documented complete doxorubicin intercalation in two simulations, one for each DNA fragment.
- Identified a novel 'locally cooperative flipping-intercalation' mechanism involving base pair opening and flipping, distinct from the 'rise-insertion' model.
Conclusions:
- Minor groove binding is a dominant pre-intercalation step for doxorubicin.
- The observed flipping-intercalation mechanism provides new insights into drug-DNA interactions.
- Validated the AMBER force fields for accurate atomistic simulations of drug-DNA binding.
