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Updated: Aug 26, 2025
Isolation of Salmonella typhimurium-containing Phagosomes from Macrophages
Published on: October 25, 2017
Identification of natural small molecule modulators of MurB from Salmonella enterica serovar Typhi Ty2 strain using
Md Anzarul Haque1, Mandeep Singh1, Manish Kumar Tripathi1
1Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India.
Abstract:
The increase of antibiotic-resistant bacterial pathogens has created challenges in treatment and warranted the design of antibiotics against comparatively less exploited targets. The peptidoglycan (PG) biosynthesis delineates unique pathways for the design and development of a novel class of drugs. Mur ligases are an essential component of bacterial cell wall synthesis that play a pivotal role in PG biosynthesis to maintain internal osmotic pressure and cell shape. Inhibition of these enzymes can interrupt bacterial replication and hence, form attractive targets for drug discovery. In the present work, we focused on the PG biosynthesis pathway enzyme, UDP-N-acetylpyruvylglucosamine reductase, from Salmonella enterica serovar Typhi (stMurB). Biophysical characterization of purified StMurB was performed to gauge the molecular interactions and estimate thermodynamic stability for determination of attributes for possible therapeutic intervention. The thermal melting profile of MurB was monitored by circular dichroism and validated through differential scanning calorimetry experiment. Frequently used chemical denaturants, GdmCl and urea, were employed to study the chemical-induced denaturation of stMurB. In the search for natural compound-based inhibitors, against this important drug target, an in silico virtual screening based investigation was conducted with modeled stMurB structure. The three top hits (quercetin, berberine, and scopoletin) returned were validated for complex stability through molecular dynamics simulation. Further, fluorescence binding studies were undertaken for the selected natural compounds with stMurB alone and with NADPH bound form. The compounds scopoletin and berberine, displayed lesser binding to stMurB whereas quercetin exhibited stronger binding affinity than NADPH. This study suggests that quercetin can be evolved as an inhibitor of stMurB enzyme.
Insights
Antibiotic resistance necessitates new drugs targeting bacterial cell wall synthesis. Quercetin shows strong binding affinity to Salmonella Typhi MurB, suggesting its potential as a novel antibiotic inhibitor.
Area of Science:
- Microbiology and Biochemistry
- Drug Discovery and Development
Background:
- Rising antibiotic resistance demands novel therapeutic targets.
- Peptidoglycan biosynthesis is a validated target for antibacterial drug development.
- Mur ligases, essential for bacterial cell wall synthesis, are attractive targets.
Purpose of the Study:
- To characterize Salmonella Typhi MurB (stMurB) for drug development.
- To identify natural compounds inhibiting stMurB using in silico and in vitro methods.
Main Methods:
- Biophysical characterization of stMurB using circular dichroism and differential scanning calorimetry.
- In silico virtual screening of natural compounds against a modeled stMurB structure.
- Molecular dynamics simulations and fluorescence binding assays to validate compound-target interactions.
Main Results:
- Purified stMurB was characterized for its biophysical properties.
- Virtual screening identified quercetin, berberine, and scopoletin as potential inhibitors.
- Quercetin demonstrated stronger binding affinity to stMurB than NADPH, indicating potent inhibition.
Conclusions:
- StMurB is a viable drug target for combating Salmonella Typhi infections.
- Quercetin is a promising natural compound for developing new antibiotics against stMurB.
