O-acetylated peptidoglycan: its occurrence, pathobiological significance, and biosynthesis

Bacterial cell walls and their structural units, particularly peptidoglycan, induce a vast variety of biological effects in host organisms. The pathobiological effects of peptidoglycan are greatly enhanced by various modifications and substitutions to its basic composition and structure. One such modification is the presence of acetyl moieties at the C-6 hydroxyl group of N-acetylmuramyl residues, and to date, 11 species of eubacteria, including some important human pathogens, such as Neisseria gonorrhoeae, Proteus mirabilis, and Staphylococcus aureus, are known to possess O-acetylated peptidoglycan. This review addresses the influence of O-acetylation of peptidoglycan on its resistance to degradation both in vitro and in vivo, the clinical importance of the modification, and the currently held views on the pathway for its biosynthesis.