Peptidoglycan or murein is a unique large macromolecule, a polysaccharide, consisting of sugars and amino acids that forms a mesh-like peptidoglycan layer outside the plasma membrane, the rigid cell wall characteristic of most bacteria. The sugar component consists of alternating residues of β-(1,4) linked N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM). Attached to the N-acetylmuramic acid is an oligopeptide chain made 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. Peptidoglycan serves a structural role in the bacterial cell wall, giving structural strength, as well as counteracting the osmotic pressure of the cytoplasm. This repetitive linking results in a dense peptidoglycan layer which is critical for maintaining cell form and withstanding high osmotic pressures, and it is regularly replaced by peptidoglycan production. Peptidoglycan hydrolysis and synthesis are two processes that must occur in order for cells to grow and multiply, a technique carried out in three stages: clipping of current material, insertion of new material, and re-crosslinking of existing material to new material.
Teichoic acids are bacterial copolymers of glycerol phosphate or ribitol phosphate and carbohydrates linked via phosphodiester bonds.
N-Acetylglucosamine (GlcNAc) is an amide derivative of the monosaccharide glucose. It is a secondary amide between glucosamine and acetic acid. It is significant in several biological systems.
Heparan sulfate (HS) is a linear polysaccharide found in all animal tissues. It occurs as a proteoglycan in which two or three HS chains are attached in close proximity to cell surface or extracellular matrix proteins. In this form, HS binds to a variety of protein ligands, including Wnt, and regulates a wide range of biological activities, including developmental processes, angiogenesis, blood coagulation, abolishing detachment activity by GrB, and tumour metastasis. HS has also been shown to serve as cellular receptor for a number of viruses, including the respiratory syncytial virus. One study suggests that cellular heparan sulfate has a role in SARS-CoV-2 Infection, particularly when the virus attaches with ACE2.
In enzymology, N-acetylglucosamine-6-phosphate deacetylase (EC 3.5.1.25), also known as GlcNAc-6-phosphate deacetylase or NagA, is an enzyme that catalyzes the deacetylation of N-acetylglucosamine-6-phosphate (GlcNAc-6-P) to glucosamine-6-phosphate (GlcN-6-P):
In enzymology, a N-acetylglucosaminylphosphatidylinositol deacetylase (EC 3.5.1.89) is an enzyme that catalyzes the chemical reaction
In enzymology, glucosamine-phosphate N-acetyltransferase (GNA) is an enzyme that catalyzes the transfer of an acetyl group from acetyl-CoA to the primary amine in glucosamide-6-phosphate, generating a free CoA and N-acetyl-D-glucosamine-6-phosphate.
In enzymology, a [Skp1-protein]-hydroxyproline N-acetylglucosaminyltransferase is an enzyme that catalyzes the chemical reaction
N-acetyl-D-glucosamine kinase is an enzyme that in humans is encoded by the NAGK gene.
N-acetylglucosamine-1-phosphodiester alpha-N-acetylglucosaminidase is an enzyme that in humans is encoded by the NAGPA gene.
The bacterial cell wall provides strength and rigidity to counteract internal osmotic pressure, and protection against the environment. The peptidoglycan layer gives the cell wall its strength, and helps maintain the overall shape of the cell. 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 process comprising three main stages:
- formation of UDP-N-acetylmuramic acid (UDPMurNAc) from N-acetylglucosamine (GlcNAc).
- addition of a short polypeptide chain to the UDPMurNAc.
- addition of a second GlcNAc to the disaccharide-pentapeptide building block and transport of this unit through the cytoplasmic membrane and incorporation into the growing peptidoglycan layer.
Protein O-GlcNAc transferase also known as OGT or O-linked N-acetylglucosaminyltransferase is an enzyme that in humans is encoded by the OGT gene. OGT catalyzes the addition of the O-GlcNAc post-translational modification to proteins.
The alpha-D-phosphohexomutases are a large superfamily of enzymes, with members in all three domains of life. Enzymes from this superfamily are ubiquitous in organisms from E. Coli to humans, and catalyze a phosphoryl transfer reaction on a phosphosugar substrate. Four well studied subgroups in the superfamily are:
- Phosphoglucomutase (PGM)
- Phosphoglucomutase/Phosphomannomutase (PGM/PMM)
- Phosphoglucosamine mutase (PNGM)
- Phosphoaceytlglucosamine mutase (PAGM)
UDP-N-acetylglucosamine kinase is an enzyme with systematic name ATP:UDP-N-acetyl-alpha-D-glucosamine 3'-phosphotransferase. This enzyme catalyses the following chemical reaction
UDP-N-acetylglucosamine—undecaprenyl-phosphate N-acetylglucosaminephosphotransferase is an enzyme with systematic name UDP-N-acetyl-alpha-D-glucosamine:ditrans,octacis-undecaprenyl phosphate N-acetyl-alpha-D-glucosaminephosphotransferase. This enzyme catalyses the following chemical reaction
Epimerox is an experimental broad-spectrum antibiotic compound being developed by scientists at the Rockefeller University and Astex Pharmaceuticals. It is a small molecule inhibitor compound that blocks the activity of the enzyme UDP-N-acetylglucosamine 2-epimerase, an epimerase enzyme that is called 2-epimerase for short.
UDP-3-O-acyl-N-acetylglucosamine deacetylase (EC 3.5.1.108, LpxC protein, LpxC enzyme, LpxC deacetylase, deacetylase LpxC, UDP-3-O-acyl-GlcNAc deacetylase, UDP-3-O-((R)-3-hydroxymyristoyl)-N-acetylglucosamine deacetylase, UDP-(3-O-acyl)-N-acetylglucosamine deacetylase, UDP-3-O-(R-3-hydroxymyristoyl)-N-acetylglucosamine deacetylase, UDP-(3-O-(R-3-hydroxymyristoyl))-N-acetylglucosamine deacetylase) is an enzyme with systematic name UDP-3-O-((3R)-3-hydroxymyristoyl)-N-acetylglucosamine amidohydrolase. This enzyme catalyses the following chemical reaction
UDP-N-acetylglucosamine 4,6-dehydratase (configuration-inverting) (EC 4.2.1.115, FlaA1, UDP-N-acetylglucosamine 5-inverting 4,6-dehydratase, PseB, UDP-N-acetylglucosamine hydro-lyase (inverting, UDP-2-acetamido-2,6-dideoxy-β-L)arabino-hex-4-ulose-forming)) is an enzyme with systematic name UDP-N-acetyl-α-D-glucosamine hydro-lyase (inverting; UDP-2-acetamido-2,6-dideoxy-β-L-arabino-hex-4-ulose-forming). This enzyme catalyses the following chemical reaction
Cyclic di-AMP is a second messenger used in signal transduction in bacteria and archaea. It is present in many Gram-positive bacteria, some Gram-negative species, and archaea of the phylum euryarchaeota.
