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Updated: Sep 27, 2025
Determination of Chemical Inhibitor Efficiency against Intracellular Toxoplasma Gondii Growth Using a Luciferase-Based Growth Assay
Published on: April 29, 2020
Identification of potent inhibitors against chorismate synthase of Toxoplasma gondii using molecular dynamics
Samayaditya Singh1, Insaf Ahmed Qureshi1
1Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad, 500 046, Telangana, India.
Abstract:
Toxoplasmosis, caused by Toxoplasma gondii, affects about 20-30% of the human population every year globally. The emergence of severe side effects of current chemotherapeutics and drug-resistant strains emphasize upon finding new therapeutics to treat toxoplasmosis. Chorismate synthase (CS) is a vital enzyme of shikimate pathway and responsible for formation of chorismate, which acts as a precursor for production of several aromatic compounds important for virulence and survival in many bacteria and protozoans. In this study, comparative modeling was employed to predict the three-dimensional structure of T. gondii chorismate synthase (TgCS) followed by its refinement and validation using various computational tools. The modeled structure of TgCS monomer shows all the conserved features of CS, particularly the beta-alpha-beta sandwich fold. Molecular docking studies has displayed that 5-enolpyruvylshikimate-3-phosphate (EPSP, substrate) and flavin mononucleotide (FMN, cofactor) bind into the active site of TgCS and all the structures (apo, binary, and ternary) were observed to be stable during molecular dynamics (MD) simulation. Subsequently, structure-based virtual screening using TgCS has inferred two of each benzofuran and EPSP analogs as the best hits on the basis of RCS, molecular interactions, ADME properties, and MD simulations. The MD data of resultant protein-ligand complex structures was subjected to calculate the binding energy through MMPBSA method, which highlights that the EPSP analogs have higher binding affinity for the substrate-binding site of TgCS in comparison to benzofuran derivatives as well as substrate. Altogether, our study could pave the way for designing and development of next generation chemotherapeutic molecules against toxoplasmosis.
Insights
New computational methods identified potential drug candidates for toxoplasmosis by targeting the essential enzyme chorismate synthase (CS). This research offers a new avenue for developing effective treatments against this widespread parasitic infection.
Area of Science:
- Biochemistry
- Parasitology
- Computational Biology
Background:
- Toxoplasmosis affects a significant portion of the global population annually.
- Current treatments for toxoplasmosis have limitations, including severe side effects and emerging drug resistance.
- Chorismate synthase (CS) is a critical enzyme in the shikimate pathway, essential for the survival and virulence of protozoan parasites like Toxoplasma gondii.
Purpose of the Study:
- To computationally predict and validate the three-dimensional structure of Toxoplasma gondii chorismate synthase (TgCS).
- To identify potential novel therapeutic agents targeting TgCS through structure-based virtual screening.
- To evaluate the binding affinity and stability of identified drug candidates with TgCS.
Main Methods:
- Comparative modeling was used to generate the 3D structure of TgCS.
- Molecular docking and molecular dynamics (MD) simulations were employed to analyze enzyme-substrate and enzyme-ligand interactions.
- Structure-based virtual screening identified potential inhibitors from benzofuran and EPSP analog libraries.
- Molecular mechanics with generalized Born surface area (MM/GBSA) calculations assessed binding energies.
Main Results:
- The modeled TgCS structure exhibited conserved features, including the beta-alpha-beta sandwich fold.
- Both the natural substrate (5-enolpyruvylshikimate-3-phosphate, EPSP) and cofactor (flavin mononucleotide, FMN) were found to bind effectively in the TgCS active site.
- MD simulations confirmed the stability of apo, binary, and ternary TgCS structures.
- Virtual screening identified specific EPSP analogs and benzofuran derivatives as promising hits with high binding affinity to TgCS.
Conclusions:
- The study successfully modeled and validated the TgCS structure, providing a basis for drug discovery.
- Identified EPSP analogs demonstrate superior binding affinity to TgCS compared to benzofuran derivatives and the natural substrate.
- These findings pave the way for the rational design of novel chemotherapeutic agents to combat toxoplasmosis.
