Underexplored Ligand-Binding Features of FabI From Staphylococcus aureus and Escherichia coli: A Comparative Pharmacophoric Modeling and Surface Mapping Approach.

The rapid spread of antimicrobial resistance, particularly among pathogens such as Staphylococcus aureus and Escherichia coli, highlights the urgent need for novel antibacterial agents with new mechanisms of action. The bacterial enoyl-acyl carrier protein reductase (FabI), an essential enzyme in fatty acid biosynthesis, represents a promising target for narrow-spectrum antimicrobials. This study aimed to define consensus pharmacophore models and interaction profiles for FabI through an integrated computational approach. ConPhar and FTMap analyses were applied to experimental structures and molecular dynamics (MD) simulations, while protein-ligand interactions from crystallographic complexes were evaluated using PLIP. Results revealed a conserved binding core involving residues Y156/Y157 and A95 in both species. We also assessed the reliability of residues located in flexible regions by comparing MD snapshots and experimental structures, as well as the contribution of inhibitor-cofactor interactions. Surface mapping identified Y146/Y147 as a key residue, consistent with its reported role in resistance mutations. Additionally, residues I200 (E. coli), V201 (S. aureus), and F203/F204 were identified as potential unexplored interaction sites. Finally, validated consensus pharmacophore models were proposed for future virtual screening and inhibitor design.