pseudopeptidoglykan

Pseudopeptidoglykan, commonly called pseudopeptidoglycan or pseudomurein, is a cell wall polymer found in certain archaea. It resembles bacterial peptidoglycan in providing structural support but differs in chemical composition and linkage patterns. The glycan backbone consists of repeating units of N-acetylglucosamine (NAG) and N-acetyl-talosaminuronic acid (NAT), linked by beta-1,3 glycosidic bonds. The attached peptide stems and cross-links diverge from bacterial patterns, forming a mesh that is not identical to bacterial peptidoglycan.

Pseudopeptidoglykan is observed in a subset of archaea, notably some methanogenic species that inhabit extreme environments. Its presence contributes to cell wall rigidity in organisms that lack bacterial-type peptidoglycan, and it reflects broader diversity in archaeal envelope architecture.

Because the glycan backbone uses beta-1,3 linkages and NAT sugars, pseudomurein is resistant to lysozyme, an enzyme that cleaves the beta-1,4 bonds of bacterial peptidoglycan. This chemical distinction also influences the activity of antibiotics that target bacterial cell wall synthesis; many such drugs have limited or no effect on cells bearing pseudopeptidoglykan. The biosynthetic enzymes involved are archaeal-specific and differ from their bacterial counterparts, underscoring divergent evolutionary approaches to constructing cell walls.

In taxonomy and studies of archaeal biology, pseudopeptidoglykan serves as a distinguishing feature of certain lineages and provides insight into the evolution and diversity of microbial cell envelopes across domains of life.