Novel non-β-lactam inhibitor of β-lactamase TEM-171 based on acylated phenoxyaniline

• Published in: Biochimie 2017-01, Vol.132, p.45-53
• Main Authors: Grigorenko, V.G., Andreeva, I.P., Rubtsova, M.Yu, Deygen, I.M., Antipin, R.L., Majouga, A.G., Egorov, A.M., Beshnova, D.A., Kallio, J., Hackenberg, C., Lamzin, V.S.
• Format: Article
• Language: English
• Subjects: Acylation; Aniline Compounds - chemistry; Aniline Compounds - pharmacology; Antibiotic resistance; Bacterial Proteins - antagonists & inhibitors; Bacterial Proteins - chemistry; Bacterial Proteins - metabolism; beta-Lactamase Inhibitors - chemistry; beta-Lactamase Inhibitors - pharmacology; beta-Lactamases - chemistry; beta-Lactamases - metabolism; Binding Sites; Catalytic Domain; Computer Simulation; Drug Discovery - methods; Electrophoresis, Polyacrylamide Gel; Fluorescence; Kinetics; Lead discovery; Molecular Docking Simulation; Molecular Structure; Non-β-lactam inhibitor; Recombinant β-lactamase TEM; Spectroscopy, Fourier Transform Infrared - methods
• ISSN: 0300-9084; 1638-6183
• DOI: 10.1016/j.biochi.2016.10.011

The microbial resistance to antibiotics is a genuine global threat. Consequently, a search of new inhibitors remains of acute importance due to the increasing spread of multidrug resistance. Here we present a new type of non-β-lactam β-lactamase inhibitor PA-34 based on natural phenoxyaniline, identified using computer-assisted screening of scaffolds related to those of known low-affinity inhibitors. The compound displays reversible competitive inhibition of bacterial β-lactamase TEM-171, with a Ki of 88 μM. Using enzyme kinetics, infra-red spectroscopy, fluorescence quenching and computer docking, we propose that the inhibitor binds at the entrance to the enzyme active site. This is a novel inhibition mechanism compared to binding covalently to the catalytic serine in the active site or non-covalently to the allosteric site. The residues involved in binding the inhibitor are conserved among molecular class A β-lactamases. The identified compound and its proposed binding mode may have a potential for a regulation of the catalytic activity of a wide range of class A β-lactamases. We also hypothesise that the presented route for finding non-β-lactam compounds may be an effective and durable approach for combating bacterial antibiotic resistance. •New type of non-β-lactam β-lactamase inhibitor based on phenoxyaniline is described.•A new binding mode – blocking access to the active site is proposed.•Binding of PA-34 inhibitor is assisted by at least two highly conserved residues.•These residues (G242 and Y105) are conserved among molecular class A β-lactamases.