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Teichoic acids (''cf.''
Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...
τεῖχος, ''teīkhos'', "wall", to be specific a fortification wall, as opposed to τοῖχος, ''toīkhos'', a regular wall) are
bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am ...
l
copolymer In polymer chemistry, a copolymer is a polymer derived from more than one species of monomer. The polymerization of monomers into copolymers is called copolymerization. Copolymers obtained from the copolymerization of two monomer species are ...
s of
glycerol phosphate Glycerol phosphate may refer to: * Glycerol 1-phosphate * Glycerol 2-phosphate * Glycerol 3-phosphate ''sn''-Glycerol 3-phosphate is the organic ion with the formula HOCH2CH(OH)CH2OPO32-. It is one of three stereoisomers of the ester of dibasi ...
or ribitol phosphate and
carbohydrate In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may o ...
s linked via phosphodiester bonds. Teichoic acids are found within the
cell wall A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mec ...
of most
Gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bact ...
bacteria such as species in the
genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...
''
Staphylococcus ''Staphylococcus'' is a genus of Gram-positive bacteria in the family Staphylococcaceae from the order Bacillales. Under the microscope, they appear spherical ( cocci), and form in grape-like clusters. ''Staphylococcus'' species are faculta ...
'', ''
Streptococcus ''Streptococcus'' is a genus of gram-positive ' (plural ) or spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales (lactic acid bacteria), in the phylum Bacillota. Cell division in streptococci occurs ...
'', ''
Bacillus ''Bacillus'' (Latin "stick") is a genus of Gram-positive, rod-shaped bacteria, a member of the phylum '' Bacillota'', with 266 named species. The term is also used to describe the shape (rod) of other so-shaped bacteria; and the plural ''Bacill ...
'', ''
Clostridium ''Clostridium'' is a genus of anaerobic, Gram-positive bacteria. Species of ''Clostridium'' inhabit soils and the intestinal tract of animals, including humans. This genus includes several significant human pathogens, including the causative a ...
'', ''
Corynebacterium ''Corynebacterium'' () is a genus of Gram-positive bacteria and most are aerobic. They are bacilli (rod-shaped), and in some phases of life they are, more specifically, club-shaped, which inspired the genus name ('' coryneform'' means "club- ...
'', and ''
Listeria ''Listeria'' is a genus of bacteria that acts as an intracellular parasite in mammals. Until 1992, 17 species were known, each containing two subspecies. By 2020, 21 species had been identified. The genus is named in honour of the British pio ...
'', and appear to extend to the surface of the
peptidoglycan 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 (murein sacculus) characteristic of most ba ...
layer. They can be covalently linked to ''N''-acetylmuramic acid or a terminal D-
alanine Alanine (symbol Ala or A), or α-alanine, is an α-amino acid that is used in the biosynthesis of proteins. It contains an amine group and a carboxylic acid group, both attached to the central carbon atom which also carries a methyl group side ...
in the
tetrapeptide A tetrapeptide is a peptide, classified as an oligopeptide, since it only consists of four amino acids joined by peptide bonds. Many tetrapeptides are pharmacologically active, often showing affinity and specificity for a variety of receptors in p ...
crosslinkage between ''N''-acetylmuramic acid units of the peptidoglycan layer, or they can be anchored in the
cytoplasmic membrane The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment (th ...
with a
lipid Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids in ...
anchor. Teichoic acid's chemical signal is CH17P4O29NOH. Teichoic acids that are anchored to the lipid membrane are referred to as
lipoteichoic acid Lipoteichoic acid (LTA) is a major constituent of the cell wall of gram-positive bacteria. These organisms have an inner (or cytoplasmic) membrane and, external to it, a thick (up to 80 nanometer) peptidoglycan layer. The structure of LTA varies ...
s (LTAs), whereas teichoic acids that are covalently bound to peptidoglycan are referred to as wall teichoic acids (WTA).


Structure

The most common structure of Wall teichoic acids are a ManNAc(β1→4)GlcNAc disaccharide with one to three glycerol phosphates attached to the C4 hydroxyl of the ManNAc residue followed by a long chain of glycerol- or ribitol phosphate repeats. Variations come in the long chain tail, which generally include sugar subunits being attached to thee sides or the body of the repeats. Four types of WTA repeats have been named, as of 2013. Lipoteichoic acids follow a similar pattern of putting most variation in the repeats, although the set of enzymes used are different, at least in the case of Type I LTA. The repeats are anchored onto the membrane via a (di)glucosyl-diacylglycerol (Glc(2)DAG) anchor. Type IV LTA from ''Streptococcus pneumoniae'' represents a special case where both types intersect: after the tail is synthesized with an undecaprenyl phosphate (C55-P) intermediate "head", different TagU/LCP (LytR-CpsA-Psr) family enzymes either attaches it to the wall to form a WTA or to the GlcDAG anchor.


Function

The main function of teichoic acids is to provide flexibility to the cell-wall by attracting cations such as calcium and potassium. Teichoic acids can be substituted with D-alanine ester residues, or D-
glucosamine Glucosamine (C6H13NO5) is an amino sugar and a prominent precursor in the biochemical synthesis of glycosylated proteins and lipids. Glucosamine is part of the structure of two polysaccharides, chitosan and chitin. Glucosamine is one of the most ...
, giving the molecule
zwitterion In chemistry, a zwitterion ( ; ), also called an inner salt or dipolar ion, is a molecule that contains an equal number of positively- and negatively-charged functional groups. : With amino acids, for example, in solution a chemical equilibrium wil ...
ic properties. These zwitterionic teichoic acids are suspected ligands for
toll-like receptor Toll-like receptors (TLRs) are a class of proteins that play a key role in the innate immune system. They are single-pass membrane-spanning receptors usually expressed on sentinel cells such as macrophages and dendritic cells, that recognize ...
s 2 and 4. Teichoic acids also assist in regulation of cell growth by limiting the ability of
autolysins Autolysins are endogenous lytic enzymes that break down the peptidoglycan components of biological cells which enables the separation of daughter cells following cell division. They are involved in cell growth, cell wall metabolism, cell division a ...
to break the β(1-4) bond between the ''N''-acetyl glucosamine and the ''N''-acetylmuramic acid. Lipoteichoic acids may also act as receptor molecules for some Gram-positive bacteriophage; however, this has not yet been conclusively supported. It is an acidic polymer and contributes negative charge to the cell wall.


Biosynthesis


WTA and Type IV LTA

Enzymes involved in the biosynthesis of WTAs have been named: TarO, TarA, TarB, TarF, TarK, and TarL. Their roles are: * TarO (, EC 2.7.8.33) starts off the process by connecting GlcNAc to a biphospho-undecaprenyl (bactoprenyl) in the inner membrane. * TarA (, EC 2.4.1.187) connects a ManNAc to the UDP-GlcNac formed by TarO via a β-(1,4) linkage. * TarB (, EC 2.7.8.44) connects a single glycerol-3-phosphate to the C4 hydroxyl of ManNAc. * TarF (, EC 2.7.8.12) connects more glycerol-3-phosphate units to the glycerol tail. In Tag-producing bacteria, this is the final step (a long glycerol tail). Otherwise it only adds one unit. * TarK (, EC 2.7.8.46) connects the initial ribitol-5-phosphate unit. It is necessary in ''
Bacillus subtilis ''Bacillus subtilis'', known also as the hay bacillus or grass bacillus, is a Gram-positive, catalase-positive bacterium, found in soil and the gastrointestinal tract of ruminants, humans and marine sponges. As a member of the genus ''Bacillus ...
'' W23 for Tar production, but ''S. aureus'' has both functions in the same TarL/K enzyme. * TarL (, EC 2.7.8.47) constructs the long ribitol-5-phosphate tail. Following the synthesis, the
ATP-binding cassette transporter The ATP-binding cassette transporters (ABC transporters) are a transport system superfamily that is one of the largest and possibly one of the oldest gene families. It is represented in all extant phyla, from prokaryotes to humans. ABC tran ...
s ( teichoic-acid-transporting ATPase) TarGH (, ) flip the cytoplasmic complex to the external surface of the inner membrane. The redundant TagTUV enzymes link this product to the cell wall. The enzymes TarI () and TarJ () are responsible for producing the substrates that lead to the polymer tail. Many of these proteins are located in a conserved gene cluster. Later (2013) studies have identified a few more enzymes that attach unique sugars to the WTA repeat units. A set of enzymes and transporters named DltABCE that adds alanines to both wall and lipo-teichoic acids were found. Note that the set of genes are named "Tag" (teichoic acid glycerol) instead of "Tar" (teichoic acid ribitol) in ''B. subtilis'' 168, which lacks the TarK/TarL enzymes. TarB/F/L/K all bear some similarities to each other, and belong to the same family (). Due to the role of ''B. subtilis'' as the main model strain, some linked UniProt entries are in fact the "Tag" ortholog as they are better annotated. The "similarity search" may be used to access the genes in the Tar-producing ''B. substilis'' W23 (BACPZ).


As an

antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention ...
drug target

This was proposed in 2004. A further review in 2013 has given more specific parts of the pathways to inhibit given newer knowledge.


See also

*
Lipoteichoic acid Lipoteichoic acid (LTA) is a major constituent of the cell wall of gram-positive bacteria. These organisms have an inner (or cytoplasmic) membrane and, external to it, a thick (up to 80 nanometer) peptidoglycan layer. The structure of LTA varies ...
– a major constituent of the
cell wall A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mec ...
of
gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bact ...
bacteria * Sir James Baddiley


References


External links

* Bioinformatic mappings (see also the EC entries): ** UniProt: WT
KW-0777pathway:547.789
(poly(glucopyranosyl N-acetylgalactosamine 1-phosphate) teichoic acid biosynthesis)
pathway:547.827
(poly(glycerol phosphate) teichoic acid biosynthesis)
pathway:547.790
(poly(ribitol phosphate) teichoic acid biosynthesis) ** UniProt: LT
pathway:547.556
(lipoteichoic acid biosynthesis) **
gene ontology The Gene Ontology (GO) is a major bioinformatics initiative to unify the representation of gene and gene product attributes across all species. More specifically, the project aims to: 1) maintain and develop its controlled vocabulary of gene and ge ...

GO:0019350
{{Bacteria Organic acids Cell biology