Stem peptide-mimicking probes for peptidoglycan labeling.

Probes	Figures	Reporter groups	Labeling mechanisms	Key enzymes	Bacteria typically used in labeling	Ref.
Single d-amino acid	NAa	Fluorescent or bio-orthogonal tag	Acyl-acceptor for 3–3 or 3–4 cross-link	Ldt; Ddt	Highly diverse	15–20
d-Amino acid-composed dipeptide	Fig. 2a	Alkyne	Lipid II synthesis	MurF	Chlamydia and others	22, 31 and 44–46
	Fig. 2d	Alkyne			Bacillus subtilis	41
	Fig. 2i	Azide			Streptococcus pneumoniae	47
	Fig. 2k	Fluorophore			Agrobacterium tumefaciens	48
Stem tripeptide	Fig. 3a	Fluorophore	PGN recycling	Mpl	Escherichia coli	50
Stem tripeptide with a linker	Fig. 4a	Fluorophore	Acyl-donor for 3-4 cross-link	PBP4	Staphylococcus aureus	52 and 55
Stem tetrapeptide	Fig. 5c	Fluorophore	Acyl-donor for 3–3 cross-link	Ldt	Enterococcus faecium; Gut microbiota	57 and 61
Stem pentapeptide	Fig. 5c	Fluorophore	Acyl-donor for 3–4 cross-link	Ddt	Enterococcus faecium	57
Stem tripeptide with a cross-bridge amino acid	Fig. 6c	Fluorophore	Acyl-acceptor for 3–3 or 3–4 cross-link	Ldt; Ddt	Enterococcus faecium	58
Stem tripeptide	Fig. 6e	Fluorophore	Acyl-acceptor for 3–3 or 3–4 cross-link	Ldt; Ddt	Mycobacterium smegmatis	60

^aNA, not available.