Towards the Native Binding Modes of Antibiotics that Target Lipid II

The alarming rise of antimicrobial resistance (AMR) imposes severe burdens on healthcare systems and the economy worldwide, urgently calling for the development of new antibiotics. Antimicrobial peptides could be ideal templates for next-generation antibiotics, due to their low propensity to cause resistance. An especially promising branch of antimicrobial peptides target lipid II, the precursor of the bacterial peptidoglycan network. To develop these peptides into clinically applicable compounds, detailed information on their pharmacologically relevant modes of action is of critical importance. Here we review the binding modes of a selection of peptides that target lipid II and highlight shortcomings in our molecular understanding that, at least partly, relate to the widespread use of artificial membrane mimics for structural studies of membrane-active antibiotics. In particular, with the example of the antimicrobial peptide nisin, we showcase how the native cellular membrane environment can be critical for understanding of the physiologically relevant binding mode.