Peptidoglycan- and Lipoteichoic Acid-induced Cell Activation Is Mediated by Toll-like Receptor 2

Polyphasic taxonomy, a consensus approach to bacterial systematics.

The cell wall envelope of gram-positive bacteria is a macromolecular, exoskeletal organelle that is assembled and turned over at designated sites. The cell wall also functions as a surface organelle that allows gram-positive pathogens to interact with their environment, in particular the tissues of the infected host. All of these functions require that surface proteins and enzymes be properly targeted to the cell wall envelope. Two basic mechanisms, cell wall sorting and targeting, have been identified. Cell well sorting is the covalent attachment of surface proteins to the peptidoglycan via a C-terminal sorting signal that contains a consensus LPXTG sequence. More than 100 proteins that possess cell wall-sorting signals, including the M proteins of Streptococcus pyogenes, protein A of Staphylococcus aureus, and several internalins of Listeria monocytogenes, have been identified. Cell wall targeting involves the noncovalent attachment of proteins to the cell surface via specialized binding domains. Several of these wall-binding domains appear to interact with secondary wall polymers that are associated with the peptidoglycan, for example teichoic acids and polysaccharides. Proteins that are targeted to the cell surface include muralytic enzymes such as autolysins, lysostaphin, and phage lytic enzymes. Other examples for targeted proteins are the surface S-layer proteins of bacilli and clostridia, as well as virulence factors required for the pathogenesis of L. monocytogenes (internalin B) and Streptococcus pneumoniae (PspA) infections. In this review we describe the mechanisms for both sorting and targeting of proteins to the envelope of gram-positive bacteria and review the functions of known surface proteins.

Surface Proteins of Gram-Positive Bacteria and Mechanisms of Their Targeting to the Cell Wall Envelope

https://pure.mpg.de/pubman/item/item_3244981_1/component/file_3244982/Jha%20et%20al..pdf

Network integration of parallel metabolic and transcriptional data reveals metabolic modules that regulate macrophage polarization.

A number of glycoproteins have oligosaccharides linked to protein in a GlcNAc----asparagine bond. These oligosaccharides may be either of the complex, the high-mannose or the hybrid structure. Each type of oligosaccharides is initially biosynthesized via lipid-linked oligosaccharides to form a Glc3Man9GlcNAc2-pyrophosphoryl-dolichol and transfer of this oligosaccharide to protein. The oligosaccharide portion is then processed, first of all by removal of all three glucose residues to give a Man9GlcNAc2-protein. This structure may be the immediate precursor to the high-mannose structure or it may be further processed by the removal of a number of mannose residues. Initially four alpha 1,2-linked mannoses are removed to give a Man5 - GlcNAc2 -protein which is then lengthened by the addition of a GlcNAc residue. This new structure, the GlcNAc- Man5 - GlcNAc2 -protein, is the substrate for mannosidase II which removes the alpha 1,3- and alpha 1,6-linked mannoses . Then the other sugars, GlcNAc, galactose, and sialic acid, are added sequentially to give the complex types of glycoproteins. A number of inhibitors have been identified that interfere with glycoprotein biosynthesis, processing, or transport. Some of these inhibitors have been valuable tools to study the reaction pathways while others have been extremely useful for examining the role of carbohydrate in glycoprotein function. For example, tunicamycin and its analogs prevent protein glycosylation by inhibiting the first step in the lipid-linked pathway, i.e., the formation of Glc NAc-pyrophosphoryl-dolichol. These antibiotics have been widely used in a number of functional studies. Another antibiotic that inhibits the lipid-linked saccharide pathway is amphomycin, which blocks the formation of dolichyl-phosphoryl-mannose. In vitro, this antibiotic gives rise to a Man5GlcNAc2 -pyrophosphoryl-dolichol from GDP-[14C]mannose, indicating that the first five mannose residues come directly from GDP-mannose rather than from dolichyl-phosphoryl-mannose. Other antibodies that have been shown to act at the lipid-level are diumycin , tsushimycin , tridecaptin, and flavomycin. In addition to these types of compounds, a number of sugar analogs such as 2-deoxyglucose, fluoroglucose , glucosamine, etc. have been utilized in some interesting experiments. Several compounds have been shown to inhibit glycoprotein processing. One of these, the alkaloid swainsonine , inhibits mannosidase II that removes alpha-1,3 and alpha-1,6 mannose residues from the GlcNAc- Man5GlcNAc2 -peptide. Thus, in cultured cells or in enveloped viruses, swainsonine causes the formation of a hybrid structure.(ABSTRACT TRUNCATED AT 400 WORDS)

Inhibitors of the Biosynthesis and Processing of N-Linked Oligosaccharide Chains

A procedure is described for measuring the extraction of lipoteichoic acids from gram-positive bacteria in absolute terms. Virtually complete extraction was achieved from various bacteria by hot phenol/water if the cells were disrupted. Extraction of whole and delipidated cells and of the membrane fraction gave considerably lower yields. Most of the nucleic acids co-extracted from disrupted cells was removed by treatment with nucleases. Nuclease-resistant nucleic acid, protein, polysaccharide, and teichoic acid were separated from lipoteichoic acid by anionexchange chromatography on DEAE-Sephacel or hydrophobic interaction chromatography on octyl-Sepharose. Purified preparations were essentially free of polymeric contaminants, retained their alanine ester substitution, and were in the sodium salt form. Hydrophobic interaction chromatography also made it possible to recognize contamination of lipoteichoic acid with its deacylated and lyso-form, and to discriminate molecular species containing two and three, or two and four acyl groups.

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1432-1033.1983.tb07495.x

Improved preparation of lipoteichoic acids.

Pulse-chase experiments with [2-3H]glycerol and [14C]acetate revealed that in Staphylococcus aureus lipoteichoic acid biosynthesis plays a dominant role in membrane lipid metabolism. In the chase, 90% of the glycerophosphate moiety of phosphatidylglycerol was incorporated into the polymer: 25 phosphatidylglycerol + diglucosyldiacylglycerol leads to (glycerophospho)25-diglucosyldiacylglycerol + 25 diacylglycerol. Glycerophosphodiglucosyldiacylglycerol was shown to be an intermediate, confirming that the hydrophilic chain is polymerized on the final lipid anchor. Total phosphatidylglycerol served as the precursor pool and was estimated to turn over more than twice for lipoteichoic acid synthesis in one bacterial doubling. Of the resulting diacylglycerol approximately 10% was used for the synthesis of glycolipids and the lipid anchor of lipoteichoic acid. The majority of diacylglycerol recycled via phosphatidic acid to phosphatidylglycerol. Synthesis of bisphosphatidylglycerol was negligible and only a minor fraction of phosphatidylglycerol passed through the metabolically labile lysyl derivative. In contrast to normal growth, energy deprivation caused an immediate switch-over from the synthesis of lipoteichoic acid to the synthesis of bisphosphatidylglycerol.

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1432-1033.1984.tb07923.x

The role of lipoteichoic acid biosynthesis in membrane lipid metabolism of growing Staphylococcus aureus

The metabolism of glucosamine in chick embryo fibroblasts was studied at different concentrations of the amino sugar added to the culture medium.



In glucose-containing medium the well-known metabolites, UDP-N-acetylglucosamine, N-acetylglucosamine 6-phosphate and N-acetylglucosamine, are detectable after inhibition of glycosylation resulting from glucosamine treatment. Especially when the cells were infected with influenza virus, high intracellular concentrations of non-metabolized glucosamine are demonstrable in addition.



Removal of the inhibitor from the medium results in release of the block of influenza virus glycoprotein glycosylation within 10 min. The onset of glycosylation is paralleled by a rapid reduction of intracellular levels of glucosamine without significant changes in the concentrations of its metabolites. Furthermore, concentrations of GDP-mannose, UDP-glucose, and UDP-galactose remain constant for at least 30 min after reversal of the block.



It is concluded that glucosamine as such exerts its effects on glycosylation, rather than one of its metabolites being responsible for this effect.

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1432-1033.1979.tb12920.x

H. Uwe Koch

Papers

Improved preparation of lipoteichoic acids.

The role of lipoteichoic acid biosynthesis in membrane lipid metabolism of growing Staphylococcus aureus

Glucosamine Itself Mediates Reversible Inhibition of Protein Glycosylation

Alanine ester substitution and its effect on the biological properties of lipoteichoic acids