The action of dilute alkali on some bacterial cell walls

The entry mechanism of membrane-containing phage Bam35 infecting Bacillus thuringiensis

The temperate double-stranded DNA bacteriophage Bam35 infects gram-positive Bacillus thuringiensis cells. Bam35 has an icosahedral protein coat surrounding the viral membrane that encloses the linear 15-kbp DNA genome. The protein coat of Bam35 uses the same assembly principle as that of PRD1, a lytic bacteriophage infecting gram-negative hosts. In this study, we dissected the process of Bam35 entry into discrete steps: receptor binding, peptidoglycan penetration, and interaction with the plasma membrane (PM). Bam35 very rapidly adsorbs to the cell surface, and N-acetyl-muramic acid is essential for Bam35 binding. Zymogram analysis demonstrated that peptidoglycan-hydrolyzing activity is associated with the Bam35 virion. We showed that the penetration of Bam35 through the PM is a divalent-cation-dependent process, whereas adsorption and peptidoglycan digestion are not.

Changes in wall teichoic acid during the rod-sphere transition of Bacillus subtilis 168

Wall teichoic acid (WTA) is essential for the growth of Bacillus subtilis 168. To clarify the function of this polymer, the WTAs of strains 168, 104 rodB1, and 113 tagF1 (rodC1) grown at 32 and 42 degrees C were characterized. At the restrictive temperature, the rodB1 and tagF1 (rodC1) mutants undergo a rod-to-sphere transition that is correlated with changes in the WTA content of the cell wall. The amount of WTA decreased 33% in strain 104 rodB1 and 84% in strain 113 tagF1 (rodC1) when they were grown at the restrictive temperature. The extent of alpha-D-glucosylation (0.84) was not affected by growth at the higher temperature in these strains. The degree of D-alanylation decreased from 0.22 to 0.10 in the rodB1 mutant but remained constant (0.12) in the tagF1 (rodC1) mutant at both temperatures. Under these conditions, the degree of D-alanylation in the parent strain decreased from 0.27 to 0.21. The chain lengths of WTA in strains 168 and 104 rodB1 grown at both temperatures were approximately 53 residues, with a range of 45 to 60. In contrast, although the chain length of WTA from the tagF1 (rodC1) mutant at 32 degrees C was similar to that of strains 168 and 104 rodB1, it was approximately eight residues at the restrictive temperature. The results suggested that the rodB1 mutant is partially deficient in completed poly(glycerophosphate) chains. The precise biochemical defect in this mutant remains to be determined. The results for strain 113 tagF1(rodC1) are consistent with the temperature-sensitive defect in the CDP-glycerol:poly(glycerophosphate) glycerophosphotransferase (H. M. Pooley, F.-X. Abellan, and D. Karamata, J. Bacteriol. 174:646-649, 1992).

Structural differentiation of the Bacillus subtilis 168 cell wall

Exponential-growth-phase cultures of Bacillus subtilis 168 were probed with polycationized ferritin (PCF) or concanavalin A (localized by the addition of horseradish peroxidase conjugated to colloidal gold) to distinguish surface anionic sites and teichoic acid polymers, respectively. Isolated cell walls, lysozyme-digested cell walls, and cell walls treated with mild alkali to remove teichoic acid were also treated with PCF. After labelling, whole cells and walls were processed for electron microscopy by freeze-substitution. Thin sections of untreated cells showed a triphasic, fibrous wall extending more than 30 nm beyond the cytoplasmic membrane. Measurements of wall thickness indicated that the wall was thicker at locations adjacent to septa and at pole-cylinder junctions (P < 0.001). Labelling studies showed that at saturating concentrations the PCF probe labelled the outermost limit of the cell wall, completely surrounding individual cells. However, at limiting PCF concentrations, labelling was observed at only discrete cell surface locations adjacent to or overlying septa and at the junction between pole and cylinder. Labelling was rarely observed along the cell cylinder or directly over the poles. Cells did not label along the cylindrical wall until there was visible evidence of a developing septum. Identical labelling patterns were observed by using concanavalin A-horseradish peroxidase-colloidal gold. Neither probe appeared to penetrate between the fibers of the wall. We suggest that the fibrous appearance of the wall seen in freeze-substituted cells reflects turnover of the wall matrix, that the specificity of labelling to discrete sites on the cell surface is indicative of regions of extreme hydrolytic activity in which alpha-glucose residues of the wall teichoic acids and electronegative sites (contributed by phosphate and carboxyl groups of the teichoic acids and carboxyl groups of the peptidoglycan polymers) are more readily accessible to our probes, and that the wall of exponentially growing B. subtilis cells contains regions of structural differentiation.

Genetic structure, isolation and characterization of a Bacillus licheniformis cell wall hydrolase

A DNA fragment containing the gene for a cell wall hydrolase of Bacillus licheniformis was cloned into Escherichia coli. Sequencing of the fragment showed the presence of an open reading frame which encodes a polypeptide of 253 amino acids with a molecular mass of 27,513. The gene was designated as cwlM, for cell wall lysis. The deduced amino acid sequence indicated that there is a repeated sequence consisting of 33 amino acid residues in the C-terminal region. Deletion of the C-terminal region did not lead to any loss of cell wall lytic activity. The gene product purified from E. coli cells harboring a cwlM-bearing plasmid exhibited a M(r) value of 29 kDa on SDS-polyacrylamide gels, and characterization of the specific substrate bond cleaved by CWLM indicated that the enzyme is an N-acetylmuramoyl-L-alanine amidase (EC 3.5.1.28). The enzyme hydrolyzed the cell wall of Micrococcus luteus more efficiently than those of B. licheniformis and B. subtilis, but the truncated CWLM (lacking the C-terminal region) had lost this preference. CWLM prepared from B. subtilis cells harboring a plasmid containing cwlM had a similar M(r) value to that from E. coli. Amino acid sequence homologies between CWLM and other amidases, and their protein structures are discussed.

Molecular cloning and sequencing of a major Bacillus subtilis autolysin gene

A major Bacillus subtilis 168S autolysin (N-acetylmuramoyl-L-alanine amidase [EC 3.5.1.28]) was purified and then cleaved with cyanogen bromide. The N-terminal amino acid sequence of one of the resultant peptides was determined in order to make synthetic oligonucleotides. A 2.5-kb EcoRI fragment was cloned into Escherichia coli JM109 and detected by colony hybridization by using the oligonucleotides as probes. Sequencing of the insert showed the presence of an open reading frame (designated cwlB), starting at a UUG codon, which encodes a polypeptide of 496 amino acids with a molecular mass of 52,623 Da. CWLB had a presumed signal peptide which is processed after Ala at position 24. Insertional inactivation of the cwlB gene of the B. subtilis chromosome led to an approximately 90% decrease in the total cell wall hydrolytic activity of stationary-phase cells and extraordinary resistance to cell lysis, even after 6 days of incubation at 37 degrees C. No apparent changes in cell morphology, motility, competence, sporulation, or germination were observed.

Asymmetric distribution of charge on the cell wall of Bacillus subtilis

The cell wall of Bacillus subtilis is capable of binding different kinds of metal ions. The wall-ion complex appears to be dependent on both phosphoryl from teichoic acid and carboxylate from peptidoglycan. In the present study, cationized ferritin (CF) was used as a probe for charge distribution on the wall of B. subtilis 168. Detergent-extracted cell walls bound CF only on the outer wall face. Completed cell poles bound CF, but septa did not. When the walls were permitted to autolyze briefly, binding of CF occurred on both faces. In contrast, limited hydrolysis of the walls by egg white lysozyme resulted in the penetration of CF into the wall matrix. When walls were made teichoic acid-free, CF-binding asymmetry was preserved, suggesting that carboxyl groups were oriented toward the surface. Walls with carboxylates chemically neutralized also retained charge asymmetry. Phosphate-free and carboxyl-modified walls bound CF only poorly or not at all. These results indicate that negative charges contributed by both phosphate and carboxyl are responsible for the binding of CF and that the observed asymmetry in the distribution of the label is due to the orientation of teichoic acid and muramyl peptides toward the outside of the cell wall, above the plane of the glycan strands.

Synthesis of peptidoglycan and teichoic acid in Bacillus subtilis: role of the electrochemical proton gradient

The effects of several ionophores and uncouplers on glycerol and N-acetylglucosamine incorporation by Bacillus subtilis 61360, a glycerol auxotroph, were tested at different pH values. In particular, the effect of valinomycin on the synthesis of teichoic acid and peptidoglycan was examined in more detail in both growing cells and in vitro biosynthetic systems. Valinomycin inhibited synthesis of wall teichoic acid and peptidoglycan in whole cells but not in the comparable in vitro systems. It did not inhibit formation of free lipid or lipoteichoic acid. The results were consistent with a role for the electrochemical proton gradient in maintaining full activity of cell wall synthetic enzymes in intact cells. Such an energy source would be required for a model in which rotation or reorientation of synthetic enzyme complexes is envisaged for the translocation of wall precursor molecules across the cytoplasmic membrane (Harrington and Baddiley, J. Bacteriol. 155:776-792, 1983).

Teichoicase from Bacillus subtilis Marburg

The properties of a teichoic acid degrading enzyme (teichoicase) isolated from Bacillus subtilis Marburg are described. The purified enzyme showed phosphodiesterase activity but not phosphomonoesterase activity, and it had an absolute substrate specificity for alpha-glucosylated glycerol teichoic acid, the endogenous cell wall teichoic acid of the enzyme-producing cell. The substrate was degraded by an exo-mechanism yielding the monomer alpha-D-glucose 1 leads to 2 (sn)glycero-3-phosphate. When B. subtilis Marburg was grown in a rich medium, enzyme activity was detected in extracts from sporulating cells. Teichoicase activity was present in a mutant blocked in stage II of the sporulation process but was absent in a mutant blocked in stage O. It was concluded that teichoicase is active on enzyme-producing cells since the reaction product could be detected in their culture supernatant. Attempts to demonstrate analogous enzyme activity in other Bacillus strains failed. The enzyme could be used for the rapid detection of alpha-glucosylated glycerol teichoic acid and for the controlled alteration of native bacterial cell surfaces exhibiting the appropriate structure.

Purification, Mr-value and subunit structure of a teichoic acid hydrolase from Bacillus subtilis

A teichoic acid degrading enzyme (teichoicase) was purified to apparent homogeneity from a water-soluble cell extract of sporulating Bacillus subtilis cells. A rapid test for the detection of teichoicase activity was developed. The purified teichoicase has an app. Mr = 310 000. It consists of 4 identical subunits of Mr = 78 000 each.

Major sites of metal binding in Bacillus licheniformis walls

Isolated and purified walls of Bacillus licheniformis NCTC 6346 his contained peptidoglycan, teichoic acid, and teichuronic acid (0.36 mumol of diaminopimelic acid, 0.85 mumol of organic phosphorus, and 0.43 mumol of glucuronic acid per mg [dry weight] of walls, respectively). The walls also contained a total of 0.208 mumol of metal per mg. When these walls were subjected to metal-binding conditions (T. J. Beveridge and R. G. E. Murray, J. Bacteriol. 127:1502-1518, 1976) for nine metals, the amount of bound metal above background ranged from 0.910 mumol of Na to 0.031 mumol of Au per mg of walls. Most were in the 0.500-mumol mg-1 range. Electron-scattering profiles from unstained thin sections indicated that the metal was dispersed throughout the wall fabric. Mild alkali treatment extracted teichoic acid from the walls (97% based on phosphorus) but left the peptidoglycan and teichuronic acid intact. This treatment reduced their capacity for all metals but Au. Thin sections revealed that the wall thickness had been reduced by one-third, but metal was still dispersed throughout the wall fabric. Trichloroacetic acid treatment of the teichoic acid-less walls removed 95% of the teichuronic acid (based on glucuronic acid) but left the peptidoglycan intact (based on sedimentable diaminopimelic acid). The thickness of these walls was not further reduced, but little binding capacity remained (usually less than 10% of the original binding). The staining of these walls with Au produced a 14.4-nm repeat frequency within the peptidoglycan fabric. Sedimentation velocity experiments with the extracted teichuronic acid in the presence of metal confirmed it to be a potent metal-complexing polymer. These results indicated that teichoic and teichuronic acids are the prime sites of metal binding in B. licheniformis walls.

Binding of an inert, cationic osmium probe to walls of Bacillus subtilis

X-ray fluorescence spectroscopy and electron microscopy of unstained specimens have been used to study the binding of chloropentaammineosmium(III) chloride to isolated walls of Bacillus subtilis. Native walls bound 0.220 mumol of the osmium probe per mg (dry weight) of walls, whereas walls which were chemically treated to neutralize the available carboxylate groups of the peptidoglycan bound only 0.040 mumol. Teichoic acid-depleted walls bound 0.210 mumol. Thin sections of all wall types showed the osmium probe to be scattered throughout the wall matrix as a small staining deposit. The results support the idea that the metal ion-binding capacity of these walls is mediated by the available carboxylate groups in the wall fabric.

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.

Sites of metal deposition in the cell wall of Bacillus subtilis

Amine and carboxyl groups of the cell wall of Bacillus subtilis were chemically modified individually to neutralize their electrochemical charge for determination of their contribution to the metal uptake process. Mild alkali treatment removed ca. 94% of the constituent teichoic acid (expressed as inorganic phosphorus) and allowed estimation of metal interaction with phosphodiester bonds. Chemical modifications of amine functions did not reduce the metal uptake values as compared to native walls, whereas extraction of teichoic acid caused a stoichiometric reduction in levels. In contrast, alteration of carboxyl groups severely limited metal deposition of most of the metals tested. X-ray diffraction and electron microscopy suggested, in this case, that the form and structure of the metal deposit could be different from that found in native walls. The observations suggest that carboxyl groups provide the major site of metal deposition in the B. subtilis wall.

Release of autolytic enzyme from Streptococcus, faecium cell walls by treatment with dilute alkali

The autolytic enzyme (endo-beta-1,4-N-acetylmuramoylhydrolase) of Streptococcus faecium (S. faecalis ATCC 9790) was released in a soluble form from insoluble cell wall-autolytic enzyme complexes by treatment with dilute NaOH at 0 degree C. Treatment of cell wall-enzyme complexes, obtained from either exponential- or stationary-phase cells, with 0.008 to 0.01 N NaOH gave maximum yields of autolytic enzyme activity. At a fixed concentration of NaOH, the yield of autolysin increased with increasing wall densities and was accompanied by the release of methylpentose and phosphorus in amounts proportional to the autolysin. Since extraction of wall-enzyme complexes with 4.5 M LiCl at 0 degree C also removed methylpentose and phosphorus, release of enzyme with NaOH did not appear to result from hydrolysis of covalent linkages. The autolytic enzyme activity released from intact cells, or cell walls, was predominantly in the later (proteinase activable) form which could be activated by trypsin or a proteinase present in commerical bovine plasma albumin.

Comparative in vivo nitrogen-15 nuclear magnetic resonance study of the cell wall components of five Gram-positive bacteria

The proton-decoupled 9.12 MHz 15N NMR spectra of 15N-labeled Bacillus subtilis, Bacillus licheniformis, Staphylococcus auresu, Streptococcus faecalis, and Micrococcus lysodeikticus intact cells, isolated cells walls, and cell wall digests have been examined. The general characteristics of Gram-positive bacteria 15N NMR spectra and described and spectral assignments are provided, which allow in vivo 15N NMR to be applied to a wide range of problems in bacterial cell wall research. The qualitative similarity of the intact cell and cell wall spectra found in each bacteria allowed the 15 N resonances observed in the proton broad-band noise-decoupled 15N NMR spectra of intact cells to be assigned to cell wall components. Each of the five Gram-positive bacteria displayed a unique set of cell wall 15N resonances, which reflected variations in the primary structure of peptidoglycans and the amounts of teichoic acid and teichuronic acid in the cell wall, as well as the dynamic properties of the cell wall polymers. Spectral assignments of cell wall 15 N resonances assigned to teichoic D-Ala residues, teichuronic acid and acetamido groups, and peptidoglycan acetamido, amide, peptide, and free amino groups have been made on the basis of specific isotopic labeling and dilution experiments, comparison of chemical shifts to literature values, determination of pH titration shifts, cell wall fractionation experiments, and comparative analysis of the cell wall lysozyme digest spectra in terms of the known primary sequences of peptide chains. All the peptidoglycan 15N peptide resonances observed in the intact cells and isolated cell walls could be accounted for by residues in the bridge or crossbar regions of the peptide chains, which indicated that only the cross-linking groups had a high degree of motional freedom. Thermal- and pH-induced conformational changes around the cross-linking D-Ala residues were detected in the B. licheniformis cell wall lysozyme digest products. Comparison of the proton broad-band noise-decoupled and gated decoupled intact cell and cell wall 15N spectra indicated that broad-band proton decoupling resulted in nulling of cytoplasmic resonances and enhancement of the cell wall resonances by the 15N [1H5 nuclear Overhauser effect.

Control of teichoic acid synthesis in Bacillus licheniformis ATCC 9945

Analysis of cell walls of Bacillus licheniformis ATCC 9945 grown under phosphate limitation showed that teichoic acid could be replaced by teichuronic acid under these conditions. Teichuronic acid, however, was always present in the walls to some extent irrespective of the growth conditions. The enzymes involved in teichoic acid synthesis were investigated and the synthesis of these was shown to be repressed when the intracellular Pi level fell. CDP-glycerol pyrophosphorylase was studied in some detail and evidence is presented to show that the enzyme is inactivated under phosphate-limited conditions. The mechanism of inactivation is unknown but it has been shown that it does not require protein synthesis de novo.

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.

Characterization of the N-acetylmuramic acid L-alanine amidase from Bacillus subtilis

The N-acetylmuramic acid L-alanine amidase from Bacillus subtilis W-23 has been purified to apparent homogeneity. The enzyme is a monomer of molecular weight 51,000, which binds extremely tightly to homologous cell walls but not to heterologous cell walls, even of the closely related strain B. subtilis ATCC 6051. This difference in binding is only in part due to differences in teichoic acid between these two strains and to a large extent appears to represent differences in the arrangement of the peptidoglycan. A comparison of the amidase from B. subtilis W-23 and the enzyme previously purified from B. subtilis ATCC 6051 (Herbold and Glaser, 1975) shows that the two proteins, which cleave the same bond and are of the same size, do not cross-react immunologically and that the two enzymes are, therefore, not closely related in structure.

Control of teichoic and teichuronic acid biosynthesis in Bacillus subtilis 168trp. Evidence for repression of enzyme synthesis and inhibition of enzyme activity

Phosphate starvation induced teichuronic acid synthesis in cells of Bacillus subtilis 168trp-which had previously been grown with excess phosphate. This induction was prevented when protein systhesis was inhibited immediately prior to phosphate starvation and under these conditions cells continued to form teichoic acid. The converse was true when phosphate was added to cells previously grown in a phosphate-limited chemostat. The increase in teichoic acid synthesis normally following phosphate addition was prevented by chloramphenicol or amino acid starvation and cells continued to make teichuronic acid. This suggestion that repression of enzyme synthesis is involved in controlling the type of wall polymer made was supported by the low levels of UDP-glucose dehydrogenase found in cells grown with excess phosphate and of CDP-glycerol pyrophosphorylase in phosphate-limited cells. The greater amounts of teichoic acid made under phosphate limitation and of teichuronic acid with excess phosphate when protein synthesis was also inhibited indicated that modulation of enzyme activity occurs. Glycerol starvation of a glycerol-requiring mutant did not derepress teichuronic acid synthesis, indicating that glycerol-containing imtermediates do not act as repressors.

Ultrastructural study of the reversion of protoplasts of Bacillus licheniformis to bacilli

The reversion of protoplasts of Bacillus licheniformis 6346 His- on a medium containing 2.5% agar has been studied in sectioned material after reaction with a ferritin-conjugated antibody specific to the peptidoglycan isolated from the walls of the bacilli. Freeze etching has also been used. Fibrils of material reacting with the antibody have been detected emerging from isolated areas of the protoplasts after 3 h of incubation. This material gradually covers the cell and can eventually (at 6 h) be seen in freeze-etched preparations as a fringe of up to 400 nm around the cells and covering the surfaces with particles that can be removed by lysozyme. At later stages the wall begins to take on a compact, well-defined appearance that can be seen in sections; however, the cells are still grossly deformed. A transitory emergence, beyond the wall of long fibers of 6 nm in diameter, takes place after about 12 h of incubation. These fibers react with the conjugated antibody and after freeze etching show a regular banded structure. They are probably indentical with the fibers isolated elsewhere (Elliott et al., 1975) and shown to contain all the wall constituents (i.e., peptidoglycan, teichoic acid, and teichuronic acid). These fibers are not detectable in the final stages of reversion.

Formation of cell wall polymers by reverting protoplasts of Bacillus licheniformis

The biosynthesis of peptidoglycan and teichoic acid by reverting protoplasts of Bacillus licheniformis 6346 His-, in cubated at 35 C on medium containing 2.5% agar, is detectable after 40 min. The amount of N-acetyl-[1-14C]glucosamine incorporated into peptidoglycan and teichoic acid on continued incubation doubles at the same rate as the incorporation of [3H]tryptophan into protein. At the early stages of reversion the average glycan chain length, measured by the ratio of free reducing groups of muramic acid and glucosamine to total muramic acid present, is very short. As reversion proceeds, the average chain length increases to a value similar to the found in the wall of the parent bacillus. The extent of cross-linkage found in the peptide side chains of the peptidoglycan also increases as reversion proceeds. At the completion of reversion the wall material synthesized has similar characteristics to those of the walls of the parent bacilli, containing peptidoglycan and teichoic and teichuronic acids in about the same proportions. Soluble peptidoglycan can be isolated from the reversion medium, amounting to 30% of the total formed after 3 h of incubation and 8% after 12 h. This amount was reduced by the presence in the medium of the walls of an autolysin-deficient mutant; they were not formed at all by reverting protoplasts of the autolysin-deficient mutant itself. Analysis of the soluble material provided additional evidence for their being autolytic products rather than small unchanged molecules. When protoplasts were incubated on medium containing only 0.8% agar, 53 to 67% of the peptidoglycan formed after 3 h of incubation was soluble, and 21% after 12 h. Fibers that appeared to be sheared from the protoplasts at intermediate stages of reversion on medium containing 2.5% agar were similar in composition to the bacillary walls.

Soluble macromolecular complexes involving bacterial teichoic acids

Cell wall and membrane teichoic acids from several bacteria formed soluble complexes with polysaccharides and bovine plasma in alkyl alcohol solutions. Polysaccharides which contain different monomeric units and anomeric configurations complexed with the teichoic acids, suggesting that the interaction is relatively nonspecific. Teichoic acids complexed glycogen or bovine plasma albumin in 50 to 97% ethanol solutions. The macromolecular association between teichoic acids and polysaccharides or proteins was independent of teichoic acid size over a threefold molecular weight range. Glycerol phosphates or an acid hydrolysate of teichoic acid would not complex to either glycogen or bovine plasma albumin in ethanol. The optimal interaction between glycogen and the Bacillus subtilis lipoteichoic acid occurred between pH 4.5 and 8.2. The ability of teichoic acids to bind polysaccharides and proteins in moderate dielectric constant solvents suggests that these polymers may serve as complexing agents for hydrophilic molecules found in membranes.

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.

The location of N-acetylgalactosamine in the walls of Bacillus subtilis 168

The N-acetylgalactosamine in the walls of Bacillus subtilis 168 occurs in two polymers. One of these contains N-acetylgalactosamine, glucose and phosphorus and is attached to the peptidoglycan through an alkali-labile bond; preliminary studies indicate that a repeating unit of this polymer is glucosyl-N-acetylgalactosamine 1-phosphate. N-Acetylgalactosamine is also associated with the peptidoglycan in a component that is not converted into the free sugar or other soluble compounds on treatment of the walls with alkali. The two polymers containing N-acetylgalactosamine are released on autolysis of the walls and can be separated by ion-exchange chromatography. As glucose 6-phosphate is produced by gentle hydrolysis of the wall with acid a third phosphate polymer, poly(glucose 1-phosphate), may occur in this wall. However, as no polymer with this structure could be separated from that containing galactosamine, its existence has not been established unequivocally. The methods described permit the study of variations in N-acetylgalactosamine content with respect to growth conditions.

A polymer of N-acetylglucosamine 1-phosphate in the wall of Staphylococcus lactis 2102

1. Walls of Staphylococcus lactis 2102 contain about 40% of a phosphorylated polysaccharide, which was isolated by extraction with cold trichloroacetic acid, with dilute NaOH, and also by digestion with a Flavobacterium peptidase. 2. The purified polymer contained equimolar proportions of N-acetylglucosamine and phosphate as its sole constituents and was readily hydrolysed under gentle acidic conditions to N-acetylglucosamine 6-phosphate. 3. Studies on the intact polymer showed that it is linear and that adjacent acetamido sugar units are joined by phosphodiester bonds between their 1- and 6-positions, the glycosidic linkages having the alpha-configuration. This polymer is thus the simplest of the known microbial wall polymers possessing sugar 1-phosphate linkages. 4. Alkali degradation of the extracted polymer proceeds predominantly in a stepwise manner from the reducing end, but evidence was obtained for the direct hydrolysis of some of the inter-unit phosphodiester groups.

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.

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

A teichuronic acid, containing glucuronic acid and N-acetylgalactosamine, was purified from acid extracts of Bacillus licheniformis 6346 cell walls as described by Janczura, Perkins & Rogers (1961). After reduction of the carboxyl function of glucuronic acid residues in the polysaccharide the reduced polymer contains equimolar amounts of N-acetylgalactosamine and glucose. Methylation of the reduced polysaccharide by the Hakamori (1964) technique showed the glucose residues to be substituted on C-4. A disaccharide, 3-O-glucuronosylgalactosamine, was isolated from partial acid hydrolysates of teichuronic acid. After N-acetylation the disaccharide produces chromogen readily on heating at pH7, in agreement with C-3 substitution of the reducing N-acetylamino sugar. Teichuronic acid also produces chromogen under the same conditions, with concurrent elimination of a modified polysaccharide from C-3 of reducing terminal N-acetylgalactosamine residues of the teichuronic acid chains. The number-average chain lengths of several preparations of teichuronic acid were estimated from the amounts of chromogen produced in comparison with the N-acetylated disaccharide. The values obtained are in good agreement with the weight-average molecular weight determined by ultracentrifugal analysis. The reducing terminals of teichuronic acid are shown to be exclusively N-acetylgalactosamine by reduction with sodium boro[(3)H]hydride. The number-average chain lengths of the teichuronic acid preparations were estimated by the extent of in corporation of tritium and are in agreement with values obtained by the other methods.