Teixobactin “Swapmers” with <scp>l</scp> Tail Stereochemistry Retain Antibiotic Activity

The unusual d-l-l-d-d-l-l pattern of stereochemistry in residues 1-7 of the peptide antibiotic teixobactin is critical to its extraordinary antibiotic activity, creating an unusual amphiphilic β-sheetlike structure that is essential to its mechanism of action. The current study sought to replace the three d-amino acids in the tail with l-amino acids while maintaining amphiphilicity. We find that swapping residues d-Gln₄ and d-<i>allo</i>-Ile₅ in <i>O</i>-acyl isopeptide prodrugs of teixobactin permits the introduction of l-stereochemistry with retention of antibiotic activity. Nevertheless, modifying the <i>N</i>-terminal stereochemistry results in a loss of antibiotic activity.