Some structural features of the teichuronic acid of Bacillus licheniformis N.C.T.C. 6346 cell walls

Archaeal Cell Walls

The cell wall of archaea, as of any other prokaryote, is surrounding the cell outside the cytoplasmic membrane and is mediating the interaction with the environment. In this regard, it can be involved in cell shape maintenance, protection against virus, heat, acidity or alkalinity. Throughout the formation of pore like structures, it can resemble a micro sieve and thereby enable or disable transport processes. In some cases, cell wall components can make up more than 10% of the whole cellular protein. So far, a great variety of different cell envelope structures and compounds have be found and described in detail. From all archaeal cell walls described so far, the most common structure is the S-layer. Other archaeal cell wall structures are pseudomurein, methanochondroitin, glutaminylglycan, sulfated heteropolysaccharides and protein sheaths and they are sometimes associated with additional proteins and protein complexes like the STABLE protease or the bindosome. Recent advances in electron microscopy also illustrated the presence of an outer(most) cellular membrane within several archaeal groups, comparable to the Gram-negative cell wall within bacteria. Each new cell wall structure that can be investigated in detail and that can be assigned with a specific function helps us to understand, how the earliest cells on earth might have looked like.

The biosynthesis and linkage of teichuronic acid to peptidoglycan in Bacillus licheniformis

Membrane and wall-membrane preparations of Bacillus licheniformis 94 will, if supplied with the appropriate precursors, synthesize teichuronic acid and link it to peptidoglycan although teichuronic acid is absent from walls of this organism. B. licheniformis 94 lacks phosphoglucomutase activity and therefore cannot synthesize the precursor UDPglucuronic acid. The initial reaction of teichuronic acid biosynthesis is catalysed by a translocase and results in the formation of polyprenyl-diphospho-N-acetylgalactosamine and the release of UMP. This reaction is not inhibited by tunicamycin. The disaccharide repeating unit of the polymer is then formed by the transfer of glucuronic acid from UDPglucuronic acid with the release of UDP. Polymerization of the repeating units occurs by incorporation of new units at the reducing terminus of the growing teichuronic acid chain and the release of polyprenyl diphosphate. The subsequent dephosphorylation of the lipid diphosphate for reuse in the biosynthesis cycle is inhibited by bacitracin. Linkage to peptidoglycan occurs by the formation of a phosphodiester bond between the reducing N-acetylgalactosamine terminus of the teichuronic acid chain and a 6-hydroxyl group of a muramic acid residue in the glycan of peptidoglycan. Wall-membrane preparations synthesizing teichuronic acid, poly(glycerol phosphate) teichoic acid and peptidoglycan link the teichuronic and teichoic acids to different glycan chains.

Teichoic and teichuronic acids: biosynthesis, assembly, and location

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The structure of the capsular polysaccharide (K5 antigen) of urinary-tract-infective Escherichia coli 010:K5:H4. A polymer similar to desulfo-heparin

The capsular polysaccharide was isolated from Escherichia coli 010:K5:H4; it could not be obtained from a uncapsulated (K5-) mutant. It contains N-acetylglucosamine and glucuronic acid in a molar ratio of 1:1. Acid hydrolysis of the acidic polysaccharide as well as Smith degradation and degradation by deamination of the carboxyl-reduced polysaccharide suggested that the polysaccharide is composed of a disaccharide repeating unit. The data obtained by methylation analysis and nuclear magnetic resonance spectroscopy indicated that the repeating sequence of the capsular polysaccharide is the 4-beta-glucuronyl-1,4-alpha-N-acetylglucosaminyl unit. This structure is similar to that of desulfo-heparin.

The teichuronic acid from the walls of Bacillus licheniformis A.T.C.C. 9945

The teichuronic acid of Bacillus licheniformis A.T.C.C. 9945 grown under phosphate limitation was isolated from the cell walls and purified by ion-exchange and Sephadex chromatography. The detailed structure of the polysaccharide was established by methylation analysis, periodate oxidation and partial acid hydrolysis. The polymer is composed of tetrasaccharide repeating units with the structure [GlcA beta(1 leads to 4)GlcA beta(1 leads to 3)GalNAc beta(1 leads to 6)GalNAc alpha(1 leads to 4)n. 13C n.m.r. analysis has confirmed most of the structural features of the polysaccharide and, in particular, the anomeric configurations and linkage positions of substituents. The teichuronic acid from glucose-limited cells was identical with that from cells grown under phosphate limitation.

Role of teichuronic acid in Bacillus licheniformis: defective autolysis due to deficiency of teichuronic acid in a novobiocin-resistant mutant

nov-12, a novobiocin-resistant mutant of Bacillus licheniformis ATCC 9945, grows as long chains of cells, a characteristic of autolytic-deficient (Lyt-) mutants. Isolated walls from nov-12 autolyzed at a rate equal to 5% of that displayed by wild-type walls, thus confirming the Lyt- phenotype. Protein-free nov-12 walls displayed marked resistance to, and also failure to bind, added autolysin solubilized from wild-type walls. Comparison of isolated cell walls revealed a deficiency in teichuronic acid in the mutant. Lesser differences were observed in walls of this strain, including a reduction in galactose, an increase in the proportion of peptidoglycan, and small quantitative differences in peptidoglycan composition though the proportions of protein and teichoic acid were similar in walls of both strains. Autolytic sensitivity was studied in walls in which protein, teichoic acid, and teichuronic acid were removed successively by selective extraction procedures. Autolysis of wild-type walls was unaffected by removal or protein or teichoic acid, but teichuronic acid removal rendered wild-type walls as insensitive to autolysis as mutant walls had been throughout. Therefore, in this mutant, deficiency in teichuronic acid alone leads to the Lyt- phenotype and, hence, activity and binding of autolysin(s) are dependent upon teichuronic acid but not teichoic acid. Also, the potential rate of autolysis of cell walls in this organism was correlated with the proportion of teichuronic acid in the wall. The possible significance of these findings with respect to control of autolysis and cell separation is discussed.

The teichuronic acid of cell walls of Bacillus subtilis W23 grown in a chemostat under phosphate limitation

Cell walls of Bacillus subtilis W23 contain teichuronic acid when grown in a chemostat under phosphate limitation at a low dilution rate, but teichoic acid at a higher dilution rate. The teichuronic acid was purified and shown to be a polymer of glucuronic acid and N-acetylgalactosamine.

Immunological properties of teichoic acids

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Selective extraction of polymers from cell walls of gram-positive bacteria

Brief heating of Bacillus Licheniformis cell walls at 100 degrees C in aqueous buffers of pH3.0-4.0 removes some polymers but not others from the mucopeptides. For example, relatively undegraded teichuronic acid can be extracted at 100 degrees C in 20min at pH3.0 whereas the teichoic acids are not removed. Similar specificity can be shown with walls from three other species of micro-organism.

Effect of phosphate limitation on the morphology and wall composition of Bacillus licheniformis and its phosphoglucomutase-deficient mutants

Two very poorly lytic mutants of Bacillus licheniformis 6346 that had no teichuronic acid or glucose in their walls were phosphoglucomutase deficient. The walls of the mutants were less autolytic, and the lesion in the phosphoglucomutase gene and the formation of lytic amidase seemed to be interrelated. When phosphoglucomutase was regained or the effects of the deficiency were circumvented by the presence of galactose in the medium, the lytic enzyme was partially regained. When subjected to growth limitation by the supply of inorganic phosphate, the mutants ceased to make teichoic acid, and their walls contained a greatly increased proportion of mucopeptide. Under these conditions they formed irregular spheres which changed back to rods when inorganic phosphate was supplied. Both wall and protein synthesis were necessary for the changes in morphology. An intermediate crescent-shaped cell was formed in the change from sphere to a rod. The possible relationship of this morphological change to the distribution of biosynthetic sites is discussed.

Peptidoglycan types of bacterial cell walls and their taxonomic implications

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Autolysis of Bacillus cereus cell walls and isolation of structural components

Autolysis of Bacillus cereus N.R.R.L. 569 cell walls was accompanied by hydrolysis of the majority of the 4-O-beta-N-acetylglucosaminyl-N-acetylmuramic acid linkages in mucopeptide, presumably by an endo-beta-N-acetylglucosaminidase. Hydrolysis of the N-acetylmuramyl-l-alanine linkages by an amidase also occurred. Free d-alanine residues were detected in isolated cell walls and the proportion of these residues increased during autolysis, presumably due to d-alanine carboxypeptidase action. Fractionation and analysis of the products of autolysis confirmed these results. Among the products originating from mucopeptide were a disaccharide, N-acetylmuramyl-N-acetylglucosamine, and a tetrapeptide of sequence l-Ala-d-Glu-meso-Dap-d-Ala (Dap=diaminopimelate). A dimer fraction containing a d-Ala-meso-Dap cross-link was also isolated. Two polysaccharides were obtained from the products of autolysed cell walls and from walls made soluble by Chalaropsis B glycosidase. A neutral polysaccharide accounted for about 40% of the wall and contained N-acetylglucosamine, N-acetylgalactosamine and glucose. The neutral polysaccharide isolated from wall autolysates was attached to a part of the glycan moiety of mucopeptide. The molecular weight of the complex was approx. 28000. Stoicheiometric amounts of phosphorus were present, possibly in linkages between the polysaccharide and mucopeptide moieties. The second polysaccharide accounted for 12% of the wall and was very acidic. After acidic hydrolysis of the polysaccharide, glucosamine, galactosamine and unidentified acidic substances were detected. The acid polysaccharide isolated from wall autolysates contained only traces of mucopeptide constituents and no phosphorus.

The cell wall of Bacillus licheniformis N.C.T.C. 6346. Linkage between the teichuronic acid and mucopeptide components

1. After extraction of teichoic acid from cell walls of Bacillus licheniformis with dilute alkali, the insoluble residue contains the teichuronic acid and mucopeptide components and a small amount of residual phosphorus. 2. A complex of teichuronic acid and a part of the mucopeptide was isolated from the soluble fraction obtained by lysozyme treatment of alkali extracted walls. 3. Small-molecular-weight mucopeptide fragments, not containing teichuronic acid, are obtained from the soluble fraction in yields similar to those obtained after treatment of whole walls or acid-extracted walls with lysozyme. 4. The covalent linkages between teichuronic acid and mucopeptide are broken by treatment with dilute acid. The release of teichuronic acid chains is accompanied by the hydrolysis of N-acetylgalactosaminide linkages and the exposed N-acetylgalactosamine residues form chromogen under very mild conditions, indicating that they are substituted on C-3. 5. The initial rate of formation of reactive N-acetylgalactosamine residues during mild acid hydrolysis is parallel to the rate of extraction under the same conditions of teichuronic acid from alkali-treated insoluble walls, and to the rate of acid hydrolysis of glucose 1-phosphate. 6. The results suggest that the teichuronic acid chains are attached through reducing terminals of N-acetylgalactosamine residues to phosphate groups in the mucopeptide. 7. Muramic acid phosphate was isolated from the insoluble mucopeptide remaining after extraction of walls with dilute alkali followed by dilute acid.