RESUMO
The emergence of multiple drug resistance and extreme drug resistance pathogens necessitates the continuous evaluation of the pathogenic genome to identify conserved molecular targets and their respective inhibitors. In this study, we mapped the global mutational landscape of Neisseria gonorrhoeae (an intracellular pathogen notoriously known to cause the sexually transmitted disease gonorrhoea). We identified highly variable amino acid positions in the antibiotic target genes like the penA, ponA, 23s rRNA, rpoB, gyrA, parC, mtrR and porB. Some variations are directly reported to confer resistance to the currently used front-line drugs like ceftriaxone, cefixime, azithromycin and ciprofloxacin. Further, by whole genome comparison and Shannon entropy analysis, we identified a completely conserved protein HtpX in the drug-resistant as well as susceptible isolates of N. gonorrhoeae (NgHtpX). Comparison with the only available information of Escherichia coli HtpX suggested it to be a transmembrane metalloprotease having a role in stress response. The critical zinc-binding residue of NgHtpX was mapped to E141. By applying composite high throughput screening followed by MD simulations, we identified pemirolast and thalidomide as high-energy binding ligands of NgHtpX. Following cloning and expression of the purified metal-binding domain of NgHtpX (NgHtpXd), its Zn2+ -binding (Kd = 0.4 µM) and drug-binding (pemirolast, Kd = 3.47 µM; and thalidomide, Kd = 1.04 µM) potentials were determined using in-vitro fluorescence quenching experiment. When tested on N. gonorrhoeae cultures, both the ligands imposed a dose-dependent reduction in viability. Overall, our results provide high entropy positions in the targets of presently used antibiotics, which can be further explored to understand the AMR mechanism. Additionally, HtpX and its specific inhibitors identified can be utilised effectively in managing gonococcal infections.
RESUMO
BACKGROUND: Shiga Toxin-Producing Escherichia coli (E. coli O157:H7), capable of causing serious food-borne illnesses, is extensively studied and is known to be transmitted through animal reservoirs or person-to-person contact, leading to severe disease outbreaks. The emergence of antibiotic resistance in these strains, coupled with increased adverse effects of existing therapeutics, underscores the urgent need for alternative therapeutic strategies. OBJECTIVE: This study aims to evaluate Glutamate Racemase (MurI protein) of the food-path-ogenic E. coli O157:H7 (EC MurI) as a novel drug target. Furthermore, the study seeks to identify new compounds with potential inhibitory effects against this protein. METHODS: Using computational tools, the study identified inhibitor binding sites on EC MurI and identified relevant inhibitors capable of binding to these sites. Molecular docking tech-niques were employed to assess potential hits, and selected compounds were further analyzed for their structural activity and binding affinity to the protein. RESULTS: The results of the study revealed that Frigocyclinone and Deslanoside, exhibited the best binding affinity with EC-MurI. Subsequent molecular dynamic (MD) simulations of the selected complexes indicated that both compounds were stable. This suggests that Frigocy-clinone and Deslanoside have the potential to serve as potent inhibitors of EC-MurI. CONCLUSION: In summary, this study highlights the urgent need for alternative therapies against food-pathogenic E. coli, focusing on E. coli O157:H7. Evaluation of Glutamate Race-mase as a drug target identified Frigocyclinone and Deslanoside as promising inhibitors. MD simulations indicated their stability, suggesting their potential as lead molecules for further research and treatment development.