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Peptidoglycan recognition is an evolutionarily conserved process. [25] The overall structure is similar between bacterial species, but various modifications can increase the diversity. These include modifications of the length of sugar polymers, modifications in the sugar structures, variations in cross-linking or substitutions of amino acids ...
It is a glycoside hydrolase that catalyzes the following process: Hydrolysis of (1→4)-β-linkages between N-acetylmuramic acid and N-acetyl-D-glucosamine residues in a peptidoglycan and between N-acetyl-D-glucosamine residues in chitodextrins. Peptidoglycan is the major component of gram-positive bacterial cell wall. [1]
This layered structure is called peptidoglycan (formerly called murein). GlcNAc is the monomeric unit of the polymer chitin, which forms the exoskeletons of arthropods like insects and crustaceans. It is the main component of the radulas of mollusks, the beaks of cephalopods, and a major component of the cell walls of most fungi.
The basic peptidoglycan structure of both Gram-positive and Gram-negative bacteria comprises a sheet of glycan chains connected by short cross-linking polypeptides. Biosynthesis of peptidoglycan is a multi-step (11-12 steps) process comprising three main stages: formation of UDP-N-acetylmuramic acid (UDPMurNAc) from N-acetylglucosamine (GlcNAc).
The minimal peptidoglycan fragment hydrolyzed by PGLYRP2 is MurNAc-tripeptide. [58] Hydrolysis of peptidoglycan by PGLYRP2 diminishes its pro-inflammatory activity. [72] [91] Unlike invertebrate and lower vertebrate PGRPs, mammalian PGRPs have only limited role in defense against infections.
Many of these proteins are uncharacterised, but it has been proposed that they may function mainly in peptidoglycan hydrolysis. The CHAP domain is found in a wide range of protein architectures; it is commonly associated with bacterial type SH3 domains and with several families of amidase domains.
Double-stranded DNA phage lysins tend to lie within the 25 to 40 kDa range in terms of size. A notable exception is the streptococcal PlyC endolysin, which is 114 kDa. PlyC is not only the biggest and most potent lysin, but also structurally unique since it is composed of two different gene products, PlyCA and PlyCB, with a ratio of eight PlyCB subunits for each PlyCA in its active conformation.
Peptidoglycan is made up of a polysaccharide backbone consisting of alternating N-Acetylmuramic acid (NAM) and N-acetylglucosamine (NAG) residues in equal amounts. Peptidoglycan is responsible for the rigidity of the bacterial cell wall, and for the determination of cell shape. It is relatively porous and is not considered to be a permeability ...