Structure Based in Silico Screening Revealed a Potent Acinetobacter Baumannii Ftsz Inhibitor From Asinex Antibacterial Library

Abstract

The superbug Acinetobacter baumannii is an increasingly prevalent pathogen of the intensive care units where its treatment is challenging. The identification of newer drug targets and the development of propitious therapeutics against this pathogen is of utmost importance. A drug target, cell division enzyme (FtsZ), involved in A. baumannii cytokinesis is a promising avenue for antibacterial therapy. Structure based virtual screening illustrated a lead-like molecule from Asinex antibacterial library to have the best binding affinity for the FtsZ active pocket. Computational pharmacokinetics predicted the compound to have the safest pharmacokinetics profile, thus maximizing the chances of the molecule reaching the market with enhanced efficacy and lesser toxicity. Molecular dynamics simulations in an aqueous environment revealed the flexibility of protein loop regions, and upward extension followed by the backward movement of the inhibitor N, N-dimethylpyridazin-3-amine ring on its axis. The active pocket residue Thr310 demonstrated to play significant role in inhibitor binding. The binding free energy predicted by MM/GBSA and MM/PBSA reflected system stability with a total value of -62.15 kcal/mol and -10.60 kcal/mol, respectively. The absolute binding free energy estimated by WaterSwap was -16 kcal/mol that validates and affirms complex stability. The inhibitor represents a promising scaffold as a lead optimization for the FtsZ enzyme.