Pseudopeptidoglycan

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Structural formula of N-acetyltalosaminuronic acid
Structural formula of N-acetylglucosamine

The pseudopeptidoglycan or pseudomurein is a substance that occurs as a cell wall in archaea . It is a polysaccharide to which short amino acid chains are bound.

It is very similar to murein and consists of a chain of alternating N-acetylglucosamine and N-acetyltalosaminuronic acid units, which are β-1,3-glycosidically linked. The N-acetyl talosaminuronic acid (TalNAc) replaces the N-acetyl muramic acid of the peptidoglycan in the pseudopeptidoglycan .

The individual pseudopeptidoglycan strands are linked to one another via peptides. Each TalNAc is cross -linked to a TalNAc of another strand via the peptide chain Glu - Ala - Lys -Glu-Lys-Ala-Glu. In contrast to murein, however, there are no D -amino acids here. The stable glycosidic bond and the high degree of cross-linking of several layers of pseudopeptidoglycan give the cell wall its strength.

Due to the β-1,3-glycosidic bond, pseudomurein is insensitive to the effects of lysozyme .

The investigation of the structure of pseudopeptidoglycan was advanced because it and the murein of the "usual" bacteria have the same task in the stabilization of unicellular cells, but should have evolved independently of one another. It was assumed that structural correspondences would therefore indicate details that are essential for the function. This, in turn, is important because the action of penicillins is to create "voids" in the murein network for growing bacteria (so that it fails), and the architecture of the peptidoglycan networks for the development of such antibiotics should be known.

Schematic representation of pseudopeptidoglycan as it occurs in some archaea. N-acetyltalosaminuronic acid (TalANAc) and N-acetylglucosamine (GlcNAc) are β-1,3-glycosidically linked.

Individual evidence

  1. ↑ a b Georg Fuchs (Ed.), Hans. G. Schlegel (Author): General Microbiology . Thieme Verlag Stuttgart; 8th edition 2007; ISBN 3-13-444608-1 ; P. 135
  2. ↑ Otto Kandler (1979): Arch. Microbiol. 123, pages 295-299

literature

  • Koenig, H. et al. (1983): The primary structure of the glycan moiety of pseudomurein from Methanobacterium thermoautotrophicum . In: Hoppe Seylers Z Physiol Chem . 364 (6); 627-636; PMID 6884989 .
  • Leps, B. et al. (1984): A new proposal for the primary and secondary structure of the glycan moiety of pseudomurein. Conformational energy calculations on the glycan strands with talosaminuronic acid in 1C conformation and comparison with murein . In: Eur J Biochem . 144 (2); 279-286; PMID 6548447 .