Peptidoglycan structure

The peptidoglycan structure of bacterial cell walls. The shaded areas represent points of attachment of this macromolecule to the rest of the cell wall. The amino sugar units are joined end to end to form long, straight chains. The peptides form cross-links when the amino group of a meso-diaminopimelic acid in one chain replaces the terminal alanine in another chain. Source ... 

Figure 20-9 Biosynthesis of bacterial peptidoglycans. See Fig. 8-29 for details of the peptidoglycan structures. Green arrows show alternative route used by gram-positive bacteria.

J Garcia-Bustos, A Tomasz. A biological price of antibiotic resistance major changes in the peptidoglycan structure of penicillin-resistant strains of Streptococcus pneumoniae. Proc Natl Acad Sci (USA) 87 5414-5419, 1990. 

Figure 6-1. A peptidoglycan structure. (R is an L-alanyl-D-glutamyl-L-lysyl-D-alanine D-amino acid residues occur here.)...

Figure 11 Structures of key molecules In peptidoglycan biosynthesis (a) MurNAc-pentapeptIde (b) Lipid I and Lipid II (GIcNAc residue added by MurG Is shown In red) (c) Lipid IV and the cross-linked peptidoglycan structure.

The situation in Gram-positive bacteria is more complex because of the wide variation in peptidoglycan structure (Ghuysen, 1977). The major PBP is a low molecular weight D,D-carboxypeptidase but in none has it been demonstrated unequivocally to be the lethal target. 

Figure 1.6 Sites at which Enzymes Attack Peptidoglycan (Symbols for peptidoglycan structure as in Figure 1.2)...

Figure 3.28 Diagrammatic Representation of the Insertion of Lipoprotein Into Outer Membrane. The diagram shows a bound-lipoprotein molecule linked to the diaminopimelic acid residue (DPM) of peptidoglycan by its terminal lysine. In free-lipoprotein this terminal lysine would be unsubstituted. Bound lipoprotein can be liberated by trypsin, which cleaves the polypeptide at points marked by arrows. (The symbols used for peptidoglycan structure are as in Figure 1.2.)...

---