Metabolic Profiling of Bacteria by Unnatural C‐terminated D‐Amino Acids

Bacterial peptidoglycan is a mesh‐like network comprised of sugars and oligopeptides. Transpeptidases cross‐link peptidoglycan oligopeptides to provide vital cell wall rigidity and structural support. It was recently discovered that the same transpeptidases catalyze the metabolic incorporation of exogenous D ‐amino acids onto bacterial cell surfaces with vast promiscuity for the side‐chain identity. It is now shown that this enzymatic promiscuity is not exclusive to side chains, but that C‐terminus variations can also be accommodated across a diverse range of bacteria. Atomic force microscopy analysis revealed that the incorporation of C‐terminus amidated D ‐amino acids onto bacterial surfaces substantially reduced the cell wall stiffness. We exploited the promiscuity of bacterial transpeptidases to develop a novel assay for profiling different bacterial species.