Cracking a cancer code DNA methylation in epigenetic modification: an in-silico approach on efficacy assessment of Sri Lanka-oriented nutraceuticals

DNA methyltransferase (DNMTs) are essential epigenetic modifiers that play a critical role in gene regulation. These enzymes add a methyl group to cytosine's 5'-carbon, specifically within CpG dinucleotides, using S-adenosyl-L-methionine. Abnormal overexpression of DNMTs can alter the gene expression patterns and contribute to cancer development in the human body. Therefore, the inhibition of DNMT is a promising therapeutic approach to cancer treatment. This study was aimed to identify potential nutraceutical inhibitors from the Sri Lanka Flora database using computational methods, which provided an atomic-level description of the drug binding site and examined the interactions between nutraceuticals and amino acids of the DNMT enzyme. A series of nutraceuticals from Sri Lanka-oriented plants were selected and evaluated to assess their inhibitory effects on DNMT using absorption, distribution, metabolism, excretion and toxicity analysis, virtual screening, molecular docking, molecular dynamics simulation and trajectory analysis. Azacitidine, a DNMT inhibitor approved by the US Food and Drug Administration, was selected as a reference inhibitor. The complexes with more negative binding energies were selected and further assessed for their potency. Seven molecules were identified from 200 nutraceuticals, demonstrating significantly negative binding energies against the DNMT enzyme. Various trajectory analyses were conducted to investigate the stability of the DNMT enzyme. The results indicated that petchicine (NP#0003), ouregidione (NP#0011) and azacitidine increased the stability of the DNMT enzyme. Consequently, these two nutraceuticals showed inhibitory efficacies similar to azacitidine, making them potential candidates for therapeutic interventions targeting DNMT enzyme-related cancers. Additional bioassay testing is recommended to confirm the efficacies of these nutraceuticals and explore their applicability in clinical treatments.Communicated by Ramaswamy H. Sarma.

Computational investigation of impact of Pb(II) and Ni(II) ions on hUNG enzyme: insights from molecular dynamics simulations

Human uracil DNA glycosylase (hUNG), a crucial player in the initiation of the base excision repair pathway, is susceptible to alterations in function and conformation induced by the accumulation of toxic metals. Despite the recognized impact of toxic metals on DNA repair enzymes, there exists a notable deficiency in theoretical investigations addressing this phenomenon. This study investigates the impact of toxic heavy metal ions, Pb(II) and Ni(II), on the stability of hUNG through molecular dynamics (MD) simulations. The initial analysis involved the identification of key cavities in the hUNG enzyme. Notably, the active site cavity emerged as a promising site for ligand binding. Subsequently, AutoDockTools software was employed to dock Pb(II) and Ni(II) onto the identified cavities, followed by extensive MD simulations. The MD analysis, encompassing parameters such as root mean square deviation, radius of gyration, solvent accessible surface area, hydrogen bond variations, Ramachandran plot, principal component analysis, and root mean square fluctuations, collectively revealed distinct alterations in the behavior of the enzyme upon complexation with Pb(II) and Ni(II). Interestingly, the enzyme exhibited enhanced structural stability, reduced flexibility, and modified hydrogen bonding patterns in the presence of these toxic metal ions. The observed limitation in structural flexibility implies a more rigid and stable conformation when the enzyme complex with Pb(II) and Ni(II) compared to its free form. This structural alteration may lead to a potential reduction in enzymatic activity, suggesting that toxic metal ions influence the functional dynamics of hUNG. These computational findings offer valuable insights into the molecular interactions between metal ions and enzymes.Communicated by Ramaswamy H. Sarma.

Impact of Cd(II) on the stability of human uracil DNA glycosylase enzyme; an implication of molecular dynamics trajectories on stability analysis

Uracil DNA glycosylase is a key enzyme that identifies and removes damaged bases from DNA in the base excision repair pathway. Experimentalists have identified the possibility of Cd(II) reducing the activity of human uracil DNA glycosylase (hUNG) by binding with the enzyme replacing the catalytic water molecule. The present study focus on the stability variation of the enzyme in the presence and absence of Cd(II) and confirms the reported results with the stability analysis done using molecular dynamic (MD) simulation trajectories. The CavityPlus web server identified seven cavities for the free enzyme as possible binding sites and a cavity containing the active site of the enzyme as the best binding cavity for a ligand. Based on the CavityPlus results and the previously reported work, a free hUNG system and two systems of the enzyme with Cd(II); one with Cd(II) replacing the catalytic water molecule in the active site of the enzyme and the other replacing a non-catalytic water molecule in the active site were generated for the simulation. The simulation trajectories were used for the structural stability analysis of the enzyme in all three systems. The binding free energy of the Cd(II) with the enzyme was calculated using molecular mechanics Poisson Boltzmann surface area method. The results showed that the enzyme achieves comparatively high stability with the removal of catalytic water of the enzyme by Cd(II). Therefore, this supports the previously reported idea that Cd(II) replaces catalytic water molecules and affects enzyme activity.

Electrostatics in Computational Biophysics and Its Implications for Disease Effects

This review outlines the role of electrostatics in computational molecular biophysics and its implication in altering wild-type characteristics of biological macromolecules, and thus the contribution of electrostatics to disease mechanisms. The work is not intended to review existing computational approaches or to propose further developments. Instead, it summarizes the outcomes of relevant studies and provides a generalized classification of major mechanisms that involve electrostatic effects in both wild-type and mutant biological macromolecules. It emphasizes the complex role of electrostatics in molecular biophysics, such that the long range of electrostatic interactions causes them to dominate all other forces at distances larger than several Angstroms, while at the same time, the alteration of short-range wild-type electrostatic pairwise interactions can have pronounced effects as well. Because of this dual nature of electrostatic interactions, being dominant at long-range and being very specific at short-range, their implications for wild-type structure and function are quite pronounced. Therefore, any disruption of the complex electrostatic network of interactions may abolish wild-type functionality and could be the dominant factor contributing to pathogenicity. However, we also outline that due to the plasticity of biological macromolecules, the effect of amino acid mutation may be reduced, and thus a charge deletion or insertion may not necessarily be deleterious.