Subtractive Proteomics-Based Prioritization of Drug Targets in Enterococcus faecalis V583 and Structure-Based Identification of Plant-Derived Inhibitors Targeting Alanine Racemase: A High Priority Target.

Enterococcus faecalis, a Gram-positive facultative anaerobe, is a typical inhabitant of the human gut microbiota but becomes an opportunistic pathogen when translocated, leading to serious infections such as meningitis and bloodstream infections (BSIs). According to the World Health Organization (WHO) and recent studies, E. faecalis is responsible for a significant number of BSIs and is listed as a high-priority pathogen for antimicrobial research due to its high antibiotic resistance rates. Despite the availability of antibiotics like ampicillin, vancomycin, and amoxicillin, the emergence of resistant strains necessitates the discovery of novel drug targets. This study employed a subtractive proteomics approach to identify potential therapeutic targets in the genome of E. faecalis V583. A total of 161 essential, non-homologous proteins unique to the pathogen were identified as candidate drug targets. Among them, nine were key enzymes involved in vital metabolic pathways such as flagellar assembly, peptidoglycan biosynthesis, and amino acid metabolism. Notably, Alanine racemase (EfAlaR), essential for cell wall synthesis, was highlighted as a unique, non-homologous target. Structure-based virtual screening identified five phytochemicals, Woodfordin A (- 17.838 kcal/mol), Oenothein B (- 14.826 kcal/mol), Euphorbin H (- 14.767 kcal/mol), Pentagalloylglucose (- 14.557 kcal/mol), and Euphorbin G (- 14.526 kcal/mol) with strong binding affinities toward EfAlaR, highlighting them as promising lead compounds for the development of anti-E. faecalis therapeutics.