Chemically Induced Cell Wall Stapling in Bacteria

Cell Chem Biol. 2021 Feb 18;28(2):213-220.e4. doi: 10.1016/j.chembiol.2020.11.006. Epub 2020 Nov 24.


Transpeptidation reinforces the structure of cell-wall peptidoglycan, an extracellular heteropolymer that protects bacteria from osmotic lysis. The clinical success of transpeptidase-inhibiting β-lactam antibiotics illustrates the essentiality of these cross-linkages for cell-wall integrity, but the presence of multiple, seemingly redundant transpeptidases in many species makes it challenging to determine cross-link function. Here, we present a technique to link peptide strands by chemical rather than enzymatic reaction. We employ biocompatible click chemistry to induce triazole formation between azido- and alkynyl-d-alanine residues that are metabolically installed in the peptidoglycan of Gram-positive or Gram-negative bacteria. Synthetic triazole cross-links can be visualized using azidocoumarin-d-alanine, an amino acid derivative that undergoes fluorescent enhancement upon reaction with terminal alkynes. Cell-wall stapling protects Escherichia coli from treatment with the broad-spectrum β-lactams ampicillin and carbenicillin. Chemical control of cell-wall structure in live bacteria can provide functional insights that are orthogonal to those obtained by genetics.

Keywords: antibiotic; bacteria; cell wall; click chemistry; cross-linking; d-amino acid; metabolic labeling; peptidoglycan; transpeptidase.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Bacteria / chemistry*
  • Bacteria / drug effects
  • Bacterial Infections / drug therapy
  • Bacterial Infections / microbiology
  • Cell Wall / chemistry*
  • Cell Wall / drug effects
  • Cross-Linking Reagents / chemistry*
  • Escherichia coli / chemistry
  • Escherichia coli / drug effects
  • Humans
  • Peptides / chemistry*
  • beta-Lactams / pharmacology


  • Anti-Bacterial Agents
  • Cross-Linking Reagents
  • Peptides
  • beta-Lactams