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Antibiotic resistance is a growing global health threat that risks the lives of millions. Among the resistance mechanisms, that mediated by metallo-beta-lactamases is of particular concern as these bacterial enzymes dismantle most beta-lactam antibiotics, which are our widest applied and cheapest to produce antibiotic agents. So far, no clinically applicable metallo-beta-lactamase inhibitors are available. Aiming to adapt to structural variations, we introduce the inhibitor concept: dynamically chiral phosphonic acids. We demonstrate that they are straightforward to synthesize, penetrate bacterial membranes, inhibit the metallo-beta-lactamase enzymes NDM-1, VIM-2 and GIM-1, and are non-toxic to human cells. Mimicking the transition state of beta-lactam hydrolysis, they target the Zn ions of the metallo-beta-lactamase active site. As a unique feature, both of their stereoisomers bind metallo-beta-lactamases, which provides them unparalleled adaptability to the structural diversity of these enzymes, and may allow them to hamper bacteria's ability for resistance development.

The Global Antibiotic Research & Development Partnership (GARDP) estimates that antibiotic resistance claims one life in every 6 seconds. Antibiotic resistance is already associated with 5 million deaths annually, and this number continues to rise. A major challenge in combating antibiotic resistance is the emergence of metallo-β-lactamase enzymes that degrade the most used antibiotics, the β-lactams. Combination therapy, which involves administering an enzyme inhibitor alongside an existing β-lactam antibiotic, presents a viable strategy to address this issue. However, no metallo-β-lactamase inhibitors are currently available on the market, underscoring the urgent need for their development. This work aims to develop new phosphonic acid-based metallo-β-lac-tamase inhibitors and to study their binding interactions with the target metallo-β-lactamase enzymes. Phosphorous-containing molecules have emerged as promising inhibitor candidates as they are transition state analogues and bind to zinc ions essential for the metallo-β-lactamase activity. A set of dynamically chiral phosphinic acid-type inhibitors were synthetized through a robust and short synthetic pathway, and their biological activity was assessed. The compounds showed activity on purified metallo-β-lactamases as well as on living bacteria, they were Gram-negative membrane permeable and non-cytotoxic to human cells. Their binding event was evaluated by NMR spectroscopy, X-ray crystallography, molecular docking and dynamics studies. The key interaction between the phosphonic acid core and the enzymes' zinc ions was determined. A notable characteristic of these compounds is their ability to bind with both of their stereoisomers in the enzyme’s binding pocket due to their stereodynamically chiral behaviour. Based on these findings, the development of new phosphonic-acid type inhibitors is currently in progress. To understand better the binding of these inhibitors to different members of the metallo β-lactamase family, the NMR resonance assignment of the German-imipenemase-1 (GIM-1) has been started. This enables the evaluation of the inhibitors bound to GIM-1 in solution close to physiological conditions.