Pseudopeptidoglycan

[3] Lysozyme, a host defense mechanism present in human secretions (e.g. saliva and tears) breaks β-1,4-glycosidic bonds to degrade peptidoglycan.

[1] No archaeal enzymes are known that cleave the β-1,3-glycosidic bonds in pseudopeptidoglycan, but it can be degraded by pseudomurein endoisopeptidase encoded by two prophages.

The pathway is now known to include the orthologous-to-bacteria CarB, MurC/D (peptide ligase), MurG, MraY, UppP, UppS, and flippase presumably performing an analogous function, and two novel but conserved transmembrane proteins.

Notably, "formation of the disaccharide moiety of the glycopeptide monomer occurs before the transfer to membrane protein by MraY", as opposed to after in bacteria.

[1] Lysozyme is a natural defense mechanism in humans that has the ability to break down peptidoglycan in bacterial cells.

It attacks bacteria by targeting and inhibiting the transpeptidase that catalyzes the cross-linking of the amino sugars in peptidoglycan.

The different amino acids cause antibiotics, that target cell walls like penicillin, to be ineffective against pseudopeptidoglycan.