Peptidoglycan Layer
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A Peptidoglycan Layer is a polymer that forms the mesh-like Cell Wall of Bacteria.
- AKA: Bacteria Murein.
- Context:
- It consists of Glycan Sugars.
- It consists of Amino Acids.
- It is outside the Plasma Membrane.
- It can be:
- See: Bacteria Plasma Membrane.
References
2009
- (Wikipedia, 2009) ⇒ http://en.wikipedia.org/wiki/Peptidoglycan
- Peptidoglycan, also known as murein, is a polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of bacteria, forming the cell wall. The sugar component consists of alternating residues of β-(1,4) linked N-acetylglucosamine and N-acetylmuramic acid residues. Attached to the N-acetylmuramic acid is a peptide chain of three to five amino acids. The peptide chain can be cross-linked to the peptide chain of another strand forming the 3D mesh-like layer. Some Archaea have a similar layer of pseudopeptidoglycan or pseudomurein, where the sugar residues are β-(1,3) linked N-acetylglycosamine and N-acetyltalosaminuronic acid. That is why the cell wall of Archaea is insensitive to lysozyme. [1] Peptidoglycan serves a structural role in the bacterial cell wall, giving structural strength, as well as counteracting the osmotic pressure of the cytoplasm. A common misconception is that peptidoglycan gives the cell its shape; however, whereas peptidoglycan helps maintain the structure of the cell, it is actually the MreB protein that facilitates cell shape. Peptidoglycan is also involved in binary fission during bacterial cell reproduction. [2][3]
- The peptidoglycan layer is substantially thicker in Gram-positive bacteria (20 to 80 nanometers) than in Gram-negative bacteria (7 to 8 nanometers), with the attachment of the S-layer. Peptidoglycan forms around 90% of the dry weight of Gram-positive bacteria but only 10% of Gram-negative strains. In Gram-positive strains, it is important in attachment roles and stereotyping purposes. [4] For both Gram-positive and Gram-negative bacteria, particles of approximately 2 nm can pass through the peptidoglycan. [5]
- Gene Ontology http://amigo.geneontology.org/cgi-bin/amigo/term-details.cgi?term=GO:0009274
- Accession: GO:0009274
- Ontology: cellular component
- Synonyms
- related: murein sacculus
- narrow: peptidoglycan
- exact: cell wall (sensu Bacteria)
- broad: envelope (sensu Bacteria)
- Definition
- A protective structure outside the cytoplasmic membrane composed of peptidoglycan, a molecule made up of a glycan (sugar) backbone of repetitively alternating N-acetylglucosamine and N-acetylmuramic acid with short, attached, cross-linked peptide chains containing unusual amino acids; also called murein. As in, but not restricted to, the taxon Bacteria (Bacteria, ncbi_taxonomy_id:2). [source: GOC:mlg, ISBN:0815108893]