In the pseudomurein layer, which sugar replaces N-acetylmuramic acid (NAM) found in bacterial peptidoglycan?
Pseudomurein represents fascinating case of convergent evolution where archaeal methanogens assemble wall polymer with superficial resemblance to bacterial peptidoglycan but distinct sugar composition rendering it insensitive to many antibacterial agents. In bacterial murein, alternating N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) linked beta-1,4 carry lactyl ether with short peptide containing D-amino acids. Archaeal pseudomurein replaces NAM with N-acetyl-D-talosaminuronic acid, abbreviated NAT, which is N-acetylglucosamine epimer bearing carboxyl group at different position and
Ref: Kandler & Hippe, Arch Microbiol 1977, Pseudomurein Sacculus; Evren et al., J Bacteriol 2022, Pseudomurein Chemistry.