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Updated: Nov 5, 2025
In Vitro Characterization of Histone Chaperones using Analytical, Pull-Down and Chaperoning Assays
Published on: December 29, 2021
Comparative QM/MM Molecular Dynamics and Umbrella Sampling Simulations: Interaction of the Zinc-Bound Intermediate
Waleed A Zalloum1, Needa Zalloum2
1Department of Pharmacy, Faculty of Health Science, American University of Madaba, P.O. Box 2882, Amman 11821, Jordan.
Abstract:
Targeting the genetic material without destruction is a priority to develop safe anticancer drugs. Histone deacetylase 8 (HDAC8), which is proved to be involved in carcinogenesis, is an enzyme associated with the chromatin for post-translational deacetylation of acetylated lysine. In this study, HDAC8 co-crystallized with the intermediate state tetrapeptide Trapoxin A (TA) inhibitor and the holoenzyme are utilized to find their conformational ensembles. Furthermore, the co-crystallized intermediate gem-diolate TA was used to find optimum interactions with the active site residues by conventional molecular dynamics (MD) simulation and QM/MM umbrella sampling. Finally, the intermediate state of the acetyl-l-lysine substrate was explored by QM/MM steered MD and compared to the binding of the intermediate state of the inhibitor. This research showed that HDAC8 is flexible and exists in conformational ensembles in its holoenzyme state. Binding of the intermediate state TA stabilizes its conformation. The optimum binding to the active site of HDAC8 for structures of gem-diolate TA (intermediate state) and acetyl-l-lysine (intermediate state) was determined according to the corresponding energy profiles. The use of these models will aid in the design of potentially reversible, potent, and selective inhibitors of HDAC8 for cancer treatment.
Insights
This study reveals histone deacetylase 8 (HDAC8) flexibility and conformational ensembles. Understanding HDAC8
Area of Science:
- Biochemistry
- Molecular Biology
- Pharmacology
Background:
- Histone deacetylase 8 (HDAC8) is implicated in carcinogenesis.
- Targeting enzymes involved in chromatin regulation is crucial for developing safe anticancer drugs.
Purpose of the Study:
- To investigate the conformational dynamics of HDAC8 in its holoenzyme state.
- To determine the optimal binding interactions of intermediate state inhibitors and substrates within the HDAC8 active site.
Main Methods:
- Co-crystallization of HDAC8 with Trapoxin A (TA) inhibitor and holoenzyme.
- Conventional molecular dynamics (MD) simulations.
- QM/MM umbrella sampling and steered MD simulations.
Main Results:
- HDAC8 exhibits flexibility and exists in conformational ensembles.
- Binding of the intermediate state TA stabilizes HDAC8 conformation.
- Optimal binding energy profiles were determined for gem-diolate TA and acetyl-l-lysine intermediate states.
Conclusions:
- HDAC8 flexibility is a key characteristic of its holoenzyme state.
- Understanding intermediate binding states aids in designing potent and selective HDAC8 inhibitors.
- These models can facilitate the development of novel cancer therapeutics.
