Bioinformatic Characterization of a Candidate Antimicrobial Peptide 13_4 from Bacillus spizizenii ATCC 6633: A Multifunctional Inhibitor of Essential Metabolic Targets and β-Lactamases

The global rise of multidrug-resistant bacteria underscores the urgent need for alternative antimicrobial strategies targeting non-classical bacterial mechanisms. In this study, we performed an in-silico characterization of peptide 13_4, a short anionic peptide candidate derived from Bacillus spizizenii ATCC 6633, to explore its potential interactions with essential metabolic enzymes and resistance-associated proteins. Physicochemical analysis revealed a highly flexible, negatively charged peptide, compatible with non-membranolytic mechanisms of action. Target prospecting and molecular docking identified high-affinity interactions with key bacterial enzymes, including carbapenemases (OXA-23, OXA 24, OXA-58), Malate Synthase G, Aspartate Aminotransferase, and UDP-N-acetylglucosamine 1-carboxyvinyltransferase. Molecular dynamics simulations demonstrated stable peptide–protein complexes, supported by persistent hydrogen bonding networks and adaptive conformational flexibility, particularly for carbapenemase targets. Network analysis further highlighted the involvement of these targets in essential metabolic and resistance pathways. Collectively, these results suggest that peptide 13_4 may act as a multifunctional bioactive molecule targeting intracellular bacterial processes and resistance mechanisms, supporting its prioritization as a candidate for future experimental validation.