Teichoic acid of a stabilized L-form of Streptococcus pyogenes

Cell Wall-Deficient Bacteria as a Cause of Infections: A Review of the Clinical Significance

Cell wall-deficient bacteria (CWDB) are pleomorphic bacterial forms. These atypical organisms may occur naturally or they can be induced in the laboratory. Their presence has been known about for over a century, but a definite link to clinical disease outcomes has not been demonstrated. A number of case reports and laboratory studies suggest some disease associations, however. Considerable controversy surrounds the true relevance of CWDB to disease; there is a widespread belief that they may represent a response by the walled organism to adverse extracellular conditions like antibiotic pressure. This review looks at studies published between 1934 and 2003, which were identified by Dialog DataStar using the key words ‘cell wall deficient bacteria and clinical significance and infections’ and by further scanning the reference list at the end of the papers retrieved. We conclude that the evidence for the clinical significance of CWDB in disease is not compelling.

Surface Proteins of Gram-Positive Bacteria and How They Get There

Surface proteins are critical in determining the identifying characteristics of individual bacteria and their interaction with the environment. Because the structure of the cell surface is the major characteristic that distinguishes gram-positive from gram-negative bacteria, the processes used to transport and attach these proteins show significant differences between these bacterial classes. This review is intended to highlight these differences and to focus attention on areas that are ripe for further investigation.

A continuum of anionic charge: structures and functions of D-alanyl-teichoic acids in gram-positive bacteria

Teichoic acids (TAs) are major wall and membrane components of most gram-positive bacteria. With few exceptions, they are polymers of glycerol-phosphate or ribitol-phosphate to which are attached glycosyl and D-alanyl ester residues. Wall TA is attached to peptidoglycan via a linkage unit, whereas lipoteichoic acid is attached to glycolipid intercalated in the membrane. Together with peptidoglycan, these polymers make up a polyanionic matrix that functions in (i) cation homeostasis; (ii) trafficking of ions, nutrients, proteins, and antibiotics; (iii) regulation of autolysins; and (iv) presentation of envelope proteins. The esterification of TAs with D-alanyl esters provides a means of modulating the net anionic charge, determining the cationic binding capacity, and displaying cations in the wall. This review addresses the structures and functions of D-alanyl-TAs, the D-alanylation system encoded by the dlt operon, and the roles of TAs in cell growth. The importance of dlt in the physiology of many organisms is illustrated by the variety of mutant phenotypes. In addition, advances in our understanding of D-alanyl ester function in virulence and host-mediated responses have been made possible through targeted mutagenesis of dlt. Studies of the mechanism of D-alanylation have identified two potential targets of antibacterial action and provided possible screening reactions for designing novel agents targeted to D-alanyl-TA synthesis.

Atypical behaviour and survival of Streptococcus pyogenes L forms during intraperitoneal infection in rats

Groups of rats were injected intraperitoneally with cell wall-deficient (L) forms of Streptococcus pyogenes, with their parental (S) forms, as well as with a combined inoculum of both forms (S+L). Peritoneal exudate samples were harvested on days 1, 3, 7, 15 and 30 after challenge and were investigated by microbiological, electron microscopic, cytometric and biochemical methods. Parental S forms were isolated from peritoneal exudate samples up to day 15 post infection, while L form cultures were isolated until the end of the examined interval. Electron microscopic examination revealed continuous adhesion of L forms on the macrophage surface as well as intracellular persistence inside them. It was demonstrated that the intraperitoneal inflammatory response to L form infection was higher than to the other infections and the monocyte-macrophage populations were predominant. The established atypical behaviour and long survival of S. pyogenes L forms in the rat's peritoneum could explain some of the mechanisms of the pathogens' persistence as well as the reasons for chronic streptococcal infections.

Streptococcus pyogenes clinical isolates and lipoteichoic acid

Minimally subcultured clinical isolates of virulent nephritogenic and nonnephritogenic Streptococcus pyogenes of the same serotype showed major differences in lipoteichoic acid (LTA) production, secretion, and structure. These were related to changes in coccal adherence to and destruction of growing human skin cell monolayers in vitro. A possible relationship between cellular LTA content and group A streptococcal surface hydrophobicity was also investigated. Nephritogenic S. pyogenes M18 produced twice as much total (i.e., cellular and secretory) LTA as did the virulent, serologically identical, but nonnephritogenic isolate. Also, the LTAs from these organisms differed markedly. The polyglycerol phosphate chain of LTA from the nephritogenic isolate was longer (1.6 times) than was that from the nonnephritogenic isolate. Likewise, both LTAs indicated the presence of alanine and the absence of glucose. Amino sugars were found in LTA from only nephritogenic S. pyogenes. Teichoic acid, as a cellular component or secretory product, was not detected. The adherence of two different nephritogenic group A streptococcal serotypes (M18 and M2) exceeded that of the serologically identical but nonnephritogenic isolates (by about five times), indicating a correlation between virulent strains causing acute glomerulonephritis and adherence to human skin cell monolayers. Likewise, LTA from nephritogenic S. pyogenes M18 was more cytotoxic (1.5 times) than was that from the nonnephritogenic isolate for human skin cells, as determined by protein release. This difference was not perceptible by the more sensitive dye exclusion method (i.e., requiring less LTA), which emphasizes changes in host cell morphology and death. Also, the secretion of LTA by only virulent nephritogenic S. pyogenes M18 was exacerbated by penicillin (a maximum of four times). Finally, while the adherence of nephritogenic S. pyogenes M18 decreased markedly after continued subculturing in vitro, the surface hydrophobicity did not.

Electron microscopic localization of lipoteichoic acid on group A streptococci

The location of lipoteichoic acid (LTA) on the surface of group A streptococci was studied by immunoelectron microscopic and ultrastructural cytochemical methods, i.e. by means of LTA antibodies labelled with ferritin, or concanavalin A labelled with ferritin or colloidal gold. All these methods proved the LTA to be located on the outer cell surface of most group A streptococcus strains. The differences in the intensity of labelling paralleled the hydrophobicity of the strains, being substantially higher in the strains exhibiting a high degree of hydrophobicity. Treatment of streptococci with pronase or trypsin led to a complete loss of surface-located LTA. On the other hand, pepsin treatment of streptococci under mild conditions resulted in an increased amount of surface-located LTA in some strains. On the isolated cell walls, LTA could be demonstrated only on the outer surface of the walls. These findings correlated well with the presumed role of group A streptococcus LTA in the adherence of streptococci to the epithelial cells which is accomplished with the aid of surface-located LTA molecules.

Assembly of D-alanyl-lipoteichoic acid in Lactobacillus casei: mutants deficient in the D-alanyl ester content of this amphiphile

D-Alanyl-lipoteichoic acid (D-alanyl-LTA) from Lactobacillus casei ATCC 7469 contains a poly(glycerophosphate) moiety that is acylated with D-alanyl ester residues. The physiological function of these residues is not well understood. Five mutant strains of this organism that are deficient in the esters of this amphiphile were isolated and characterized. When compared with the parent, strains AN-1 and AN-4 incorporated less than 10% of D-[14C]alanine into LTA, whereas AN-2, AN-3, and AN-5 incorporated 50%. The synthesis of D-[14C]alanyl-lipophilic LTA was virtually absent in the first group and was approximately 30% in the second group. The mutant strains synthesized and selected the glycolipid anchor for LTA assembly. In addition, all of the strains synthesized the poly(glycerophosphate) moiety of LTA to the same extent as did the parent or to a greater extent. It was concluded that the membranes from the mutant strains AN-1 and AN-4 are defective for D-alanylation of LTA even though acceptor LTA is present. Mutant strains AN-2 and AN-3 appear to be partially deficient in the amount of the D-alanine-activating enzyme. Aberrant morphology and defective cell separation appear to result from this deficiency in D-alanyl ester content.

Interaction of purified lipoteichoic acid with the classical complement pathway

Glycerophosphate-containing lipoteichoic acids (LTAs) interact with the first component of the classical complement pathway (C1). This resulted in the activation of the classical complement pathway in serum, shown by the consumption of C1, C2, and C4. The dose-dependent interaction of LTAs with purified C1 and C1q was dependent on the negative charges of the phosphate groups of LTA. It was reduced by charge compensation through D-alanine ester substituents and by sterical hindrance through di- and trihexosyl residues linked to position 2 of the glycerol moieties. The charge density of LTA may also play a role: poly(digalactosylglycerophosphate) LTAs, in which the phosphate groups are in a greater distance from each other, were less effective, and the loss of micellar organization by deacylation of LTA drastically reduced the complement activation capacity.

Effect of streptococcal lipoteichoic acid on prolyl hydroxylase activity as related to collagen formation in mouse fibroblast monolayers

Dried and wet mouse fibroblast monolayers with labeled collagenous substrate were used to study the effects of lipoteichoic acid (LTA) on cellular prolyl hydroxylase activity. LTA is a scavenger of cations, and Fe2+ is essential for prolyl hydroxylase activity. Surprisingly, addition of LTA to dried monolayers resulted in increased prolyl hydroxylase activity, whereas preincubation of Fe2+ with LTA only negated this increase. However, significant inhibition of enzyme activity by wet monolayers occurred whether LTA was added directly to the test system or whether it was used after preincubation with Fe2+. These data suggest that LTA causes membrane perturbations. Also, that the binding of LTA to the membrane of dried and wet monolayers appears to be decidedly different when based on the subsequent availability of Fe2+ for cellular prolyl hydroxylase activity. The ability of LTA to act as a cationic exchanger and the presence of intracellular Fe2+ inaccessible to LTA probably accounted for the lack of complete inhibition of prolyl hydroxylase activity by this amphiphile in the wet cell system. Considerably less iron was needed to negate the partial inhibition of prolyl hydroxylase activity by LTA in viable cells than was needed to restore the increased enzyme activity by this amphiphile in equivalent dried preparations. These and other results showed that, although LTA does not affect collagen polypeptide chain formation in wet monolayers, its involvement at the molecular level does result in a marked decrease in the hydroxylation of collagenous peptidyl prolyl residues through LTA interaction with Fe2+. This reduction in prolyl hydroxylase activity equaled the reduction in hydroxylation of collagenous protein in fibroblast monolayers caused by LTA reported earlier (O. Leon and C. Panos, Infect. Immun. 40:785-794, 1983). Therefore, these data suggest that partial inhibition of prolyl hydroxylase activity is directly related to the synthesis of defective collagen by wet fibroblast monolayers exposed to minute amounts of group A, type 12 streptococcal LTA. Use of LTA also showed that complete inhibition of hydroxyproline formation is not required for the continued formation and accumulation of defective collagenous protein by these monolayers.

Interaction of anti-kojibiose antibody with the lipoteichoic acids from Streptococcus faecalis and Streptococcus faecium

Antisera prepared in rabbits by immunization with p-aminophenyl beta-kojibioside conjugated to bovine serum albumin (antikojibiose sera), readily agglutinated whole cells of Streptococcus faecalis or Streptococcus faecium, and showed specific reactions with the lipoteichoic acids (LTAs) of these streptococci by passive hemagglutination, microscale enzyme-linked immunosorbent assay, and crossed immunoelectrophoresis. The interaction of the antikojibiose sera with the LTAs was inhibited best by kojibiose [alpha-D-glucopyranosyl-(1----2)-D-glucose], somewhat less by the dextran from which the kojibiose was prepared, and not measurably by maltose [alpha-D-glucopyranosyl-(1----4)-D-glucose]. The sera reacted only minimally in only the most sensitive assay (microscale enzyme-linked immunosorbent assay) with LTA from group A streptococci (this LTA contains a single kojibiosyl residue as part of the glycolipid moiety of the molecule and failed to react with the Lactobacillus fermentum LTA which is substituted with alpha-D-galactopyranosyl-(1----2)-D -glucosyl units.

Teichoic acids of Streptococcus agalactiae: chemistry, cytotoxicity, and effect on bacterial adherence to human cells in tissue culture

The ratio of teichoic acid to lipoteichoic acid (LTA) in a strain of Streptococcus agalactiae type III was found to be 8:1, with the total amount of LTA being 0.1% of the dry weight of the organism. Purified teichoic acid contained D-alanine and possibly a small amount of D-glucose and was approximately 22 glycerol phosphate units in length. The linkage between each of these units was 1-3. In addition, LTA contained a complex lipid, more glucose, and an unusually high content of a short-chain fatty acid, tridecanoic acid. This LTA was cytotoxic for a variety of human cell monolayers in tissue culture, including one derived from the human central nervous system. Established human cells were more sensitive than primary cell monolayers to this LTA, with as little as 12.5 micrograms of LTA per ml being cytotoxic for HeLa cells. Teichoic acid (250 micrograms/ml) was nontoxic under identical conditions. These cytotoxicity results suggest an LTA involvement in group B streptococcal pathogenesis. Also, the first model system for the study of group B streptococcal adherence to primary human embryonic amnion cells in tissue culture is detailed. This system was used to quantitate pronounced differences in tissue tropism between S. agalactiae and Streptococcus pyogenes and showed enhanced binding by this group A coccus over that of S. agalactiae for amnion cell monolayers. The adherence of both streptococcal species to only a portion (40%) of these amnion cells suggested that host cell receptor expression may vary for primary cells in vitro. Finally, this strain of S. agalactiae was shown to adhere to amnion cells by a non-LTA-mediated mechanism. The possibility of an LTA-mediated versus a protein-mediated adherence mechanism for host cells that is related to the virulence of S. agalactiae is discussed.

Morphological changes and pathology of mouse glomeruli infected with a streptococcal L-form or exposed to lipoteichoic acid

The morphology and pathology of cultured mouse glomeruli were examined at the cellular and subcellular levels after infection with a physiological isotonic L-form of Streptococcus pyogenes type 12 or exposure to streptococcal lipoteichoic acid. These changes, as viewed by light microscopy, were identical regardless of the method used to induce glomerular cytotoxicity. They were characterized by an initial reduction in the outgrowth of cells, some cellular granulation, and later, destruction of the confluent monolayer. Once initiated, cytotoxicity could not be reversed by refeedings, and complete glomerular destruction resulted after 2 weeks. Electron microscope studies revealed that the basement membrane of intact glomeruli exposed to streptococcal lipoteichoic acid had become greatly thickened (two- to fourfold) and electron dense. Our recent biochemical findings have shown that streptococcal lipoteichoic acid increases the amount of collagen formed and retained by mouse fibroblasts in tissue culture as well as causing a reduction in the hydroxylation of proline in both intracellular and secreted collagenous material (Leon and Panos, Infect. Immun. 40:785-794, 1983). These results, together with the present findings, suggest that the thickening of the glomerular basement membrane may be due to defective collagen biosynthesis as a result of streptococcal lipoteichoic acid. The use of cultured glomeruli as a model system for studying the earliest basement membrane alterations in the absence of an immune response as a result of streptococcal lipoteichoic acid is suggested.

Cytotoxicity and inhibition of normal collagen synthesis in mouse fibroblasts by lipoteichoic acid from Streptococcus pyogenes type 12

The toxicity of lipoteichoic acid (LTA) from Streptococcus pyogenes type 12 was investigated by using mouse fibroblasts in culture in the absence of serum. Morphologically, while low concentrations of LTA elicited a subtle effect characterized by progressive cellular degeneration with practically no release of protein, larger concentrations (greater than 50 micrograms/ml) of this amphiphile resulted in rapid death of cell monolayers. Metabolic studies utilized a concentration of LTA (17.5 micrograms/ml) which caused the smallest change in cell morphology in the least number of mouse fibroblast cells per monolayer. Under these conditions, cell monolayers showed an increase of 450% in their content of collagenous protein after exposure to LTA. However, the amount of such material secreted remained unchanged. Also, changes in the type of collagenous protein formed were observed after exposure to LTA. Collagenous protein accumulating intracellularly was found to be practically hydroxyproline-free. However, collagenous protein secreted by this cell line showed a significantly reduced content of hydroxyproline as compared with control cells unexposed to this coccal membrane component. Column chromatographic studies confirmed that the collagenous protein secreted by monolayers exposed to LTA was defective (under hydroxylated). It was concluded that LTA does not affect the amount of collagenous protein secreted. However, it does increase the amount of this protein formed and retained by this cell line as well as causing a reduction in the hydroxylation of proline in both intracellular and secreted collagenous material. A possible relationship between abnormal basement membrane morphology and disturbed collagen synthesis in post-streptococcal glomerulonephritis as related to LTA is discussed.

Binding of streptococcal lipoteichoic acid to fatty acid-binding sites on human plasma fibronectin

The ability of Streptococcus pyogenes lipoteichoic acid and palmitic acid to bind to purified human plasma fibronectin was investigated. Initial studies indicated that intact fibronectin formed soluble complexes with lipoteichoic acid, resulting in a change in the mobility of fibronectin in an electrical field. Fibronectin covalently linked to agarose beads bound radiolabeled lipoteichoic acid in the acylated form but not in the deacylated form. An 18-M excess of fibronectin inhibited binding of lipoteichoic acid to the immobilized protein by 92%. Fibronectin-bound [(3)H]lipoteichoic acid could be specifically eluted with unlabeled lipoteichoic acid, as well as by fatty acid-free serum albumin. Serum albumin, which is known to contain fatty acid-binding sites capable of binding to the lipid moieties of lipoteichoic acid, inhibited the binding of lipoteichoic acid to fibronectin in a competitive fashion. The fibronectin-bound lipoteichoic acid could be eluted by 50% ethanol and various detergents but not by 1.0 M NaCl, various amino acids, or sugars. Similarly, radiolabeled palmitic acid adsorbed to fibronectin could be eluted with 50% ethanol but not with 1.0 M NaCl. Fibronectin adsorbed to a column of palmityl-Sepharose was eluted with 50% ethanol in 0.5% sodium dodecyl sulfate but not with 1.0 M NaCl or 1% sodium dodecyl sulfate alone. The binding of lipoteichoic acid to fibronectin followed first-order kinetics and was saturable. A Scatchard plot analysis of the binding data indicated a heterogeneity of lipoteichoic acid-binding sites similar to that previously found for serum albumin. Nevertheless, fibronectin contains at least one population of high-affinity binding sites for lipoteichoic acid. The binding affinity (nKa approximately 250 muM(-1)) is 2 orders of magnitude greater than the binding affinity of serum albumin. These data suggest that human plasma fibronectin contains specific binding sites for fatty acids and that lipoteichoic acid binds to these sites by way of its glycolipid moiety.

Transport of alpha-aminoisobutyric acid by Streptococcus pyogenes and its derived L-form

We studied the uptake of alpha-aminoisobutyric acid (AIB) in Streptococcus pyogenes and its physiologically isotonic L-form. S. pyogenes cells starved for glucose or treated with carbonyl cyanide-m-chlorophenyl hydrazone accumulated limited amounts of AIB. A high apparent K(m) value characterized the glucose-independent transport of AIB. The rate and extent of AIB accumulation significantly increased in the presence of glucose. Two saturable transport components with distinct apparent K(m) values characterized glycolysis-coupled transport of AIB. A biphasic Lineweaver-Burk plot was also obtained for l-alanine transport by glycolyzing S. pyogenes cells. AIB seems to share a common transport system(s) with glycine, l- and d-alanine, l-serine, and l-valine. This was shown by the competitive inhibition of AIB uptake by these compounds and their ability to induce competitive exchange efflux of accumulated AIB. About 30% of the AIB uptake was not inhibited by a saturating amount of l-valine, indicating the existence of more than one system for AIB transport. p-Chloromercuribenzoate markedly inhibited the accumulation of AIB by both glycolyzing and glucose-starved cells. In contrast, carbonyl cyanide-m-chlorophenyl hydrazone affected only metabolism-dependent uptake of AIB, which was also sensitive to dinitrophenol, N-ethylmaleimide, iodoacetate, fluoride (NaF), arsenate, and N,N'-dicyclohexylcarbodiimide. These results are interpreted according to the chemiosmotic theory of Mitchell, whereby a proton motive force constitutes the driving force for AIB accumulation. AIB was not accumulated by the L-form. However, a temporary accumulation of AIB by a counterflow mechanism and a saturable system with a low apparent affinity were demonstrated for AIB transport by this organism. We suggest that a deficiency in the coupling of energy to AIB transport is responsible for the apparent lack of active AIB accumulation by the L-form.

Teichoic and teichuronic acids: biosynthesis, assembly, and location

Images

Binding of lipoteichoic acid of group A streptococci to isolated human erythrocyte membranes

The spontaneous binding of group A streptococcal lipoteichoic acid (LTA) to mammalian cell membranes was studied in isolated membranes of human erythrocytes. The binding of radiolabeled LTA to erythrocyte membranes was dependent on membrane concentration and time. Binding approached a maximum within 30 min of incubation. The bound LTA could be displaced by adding a 50-fold excess of unlabeled LTA. The displaced LTA was eluted from a column of Sepharose 6B in a position identical to that of authentic LTA, suggesting that binding did not alter the size of the molecule. A dissociation constant of 42 micrometers was calculated, and only one population of approximately 5.5 X 10(6) binding sites per erhtyrocyte membrane was detected. Since these results suggested that erythrocyte membranes possess specific binding sites for LTA, an attempt was made to localize the putative receptors to the outside or the inside surface of the erhtyrocyte membrane. Assays of the binding of LTA to resealed right-side-out and inside-out membrane ghosts demonstrated that the outside surface was able to bind over 10 times more LTA than the inside surface. These results support the concept that the membranes possess specific binding sites for LTA and inciate that these binding sites are located almost entirely on the outside surface of erythrocyte membranes.

Erythrocyte binding properties of streptococcal lipoteichoic acids

The lipoteichoic acids (LTA) of gram-positive bacteria are known to bind spontaneously to a variety of animal cell membranes. We investigated the biological and biochemical characteristics of the binding of LTA of Streptococcus pyogenes and S. faecalis to human and sheep erythrocytes. The kinetics of the binding of the radiolabeled LTA ([(3)H]LTA) from each of these organisms to erythrocytes was similar. The dissociation constants for sheep and adult human erythrocytes were 1.6 muM and 4.5 muM, respectively, whereas that of human cord blood erythrocytes was approximately 10-fold higher, 31 muM. The number of binding sites for sheep erythrocytes was calculated to be 7.2 x x 10(6) per cell, and that of human erythrocytes, 29 x 10(6) per cell. Binding was reversible. More than 50% of bound [(3)H]LTA was displaced from erythrocytes by a 50-fold excess of unlabeled LTA. LTA prepared from heterologous species of gram-positive bacteria were all inhibitory to the binding of [(3)H]LTA whether derived from S. pyogenes or from S. faecalis. Among a number of potential receptor analogues and other inhibitors tested, including serum albumin, gangliosides Gm(2) and Gm(3), lipopolysaccharide of gram-negative bacteria, and various sugars, only albumin and the gangliosides significantly inhibited LTA binding. Trypsin or neuraminidase treatment of erythrocytes had no effect on LTA binding. Deacylation of [(3)H]LTA abolished binding ability and binding was restored by esterification of the deacylated material with stearoyl chloride, indicating that ester-linked lipids are necessary for membrane binding.

Activation of the alternative complement pathway by L-phase variants of gram-positive bacteria

The present studies were performed to investigate the potential role of the alternative complement pathway in the host's defense against bacterial L-phase variants and to gain insight into the subcellular component of gram-positive bacteria responsible for activation of the alternative pathway. L-phase variants of Staphylococcus aureus and Streptococcus faecalis were able to activate the alternative pathway and consume C3 in C4-deficient guinea pig serum in amounts comparable to their respective bacterial-phase parent organisms. Activation of the complement system via the alternative pathway resulted in death of the L-phase variants. Membranes prepared from S. faecalis L-phase variants, by either osmotic lysis or mechanical disruption, retained their ability to activate the alternative pathway. Treatment of the membranes by three different methods (water washes, hot trichloroacetic acid, and cold trichloroacetic acid) resulted in a greatly diminished ability of the membranes to activate the alternative pathway. In addition, the extracts derived from the membranes by water washes and by cold-trichloroacetic acid treatment were able to activate the alternative pathway. These studies indicate that these L-phase variants can activate the alternative pathway and suggest that membrane-associated factors play a role in the alternative pathway activation by S. faecalis L-phase variants.

The structure of C-polysaccharide from the walls of Streptococcus pneumoniae

The well-known immologically active component of pneumococci, C-polysaccharide, is a teichoic acid that can be isolated from the cell walls and purified by Sephadex and ion-exchange chromatography. Further details of the structure of C-teichoic acid were established by chemical degradation, including hydrolysis in acid and alkali, treatment with HF, periodate oxidation and methylation. In addition, the use of 13C n.m.r. has confirmed some of these structural features and resulted in a proposal for the order of substituents, the location of positions of substitution and the configuration of anomeric centres in the repeating unit of the polymer.

Effect of L-form Streptococcus pyogenes and of lipoteichoic acid on human cells in tissue culture

These studies showed the destruction of growing primary and established human cell lines with a predilection for the group A streptococci by an L-form of Streptococcus pyogenes adapted to grow in isotonic media. Also, this L-form was detected by fluorescent antibody for longer periods of time than by viable count in infected but recovered tissue culture monolayers. Additional studies with human heart cells showed changes in their protein profile and fatty acid content (but not composition) after L-form infection. This report is the first to show that the morphological changes and death of human kidney cells by this viable L-form were mimicked by the structurally different lipoteichoic acids from this organism and its parental streptococcus. These lipoteichoic acids were also equally effective in preventing attachment of S. pyogenes to human cell monolayers, but their deacylation obviated these two activities. Finally, the attachment of the isotonic L-form, as well as the parental streptococcus, to growing human kidney cells suggested that a rigid cell wall is not a prerequisite for host attachment in vitro.

Interaction of Streptococcus mutans glucosyltransferases with antibodies

1) The GTF-A and GTF-B activities of serotype (c), (e), and (f) organisms are antigenically more closely related to each other than to the comparable enzymes from organisms of the other four S. mutans serotypes. 2) The adherence-inhibiting antibody in anti-GTF-A appears to be mediated against a heat sensitive cell surface antigen of S. mutans - most likely GTF activity. However, unequivocal proof of this conclusion awaits the preparations of homogeneous GTF-A preparations.

Interaction of lipoteichoic acid of group A streptococci with human platelets

The interaction of group A streptococcal lipoteichoic acid (LTA) with mammalian cell membranes was studied in human platelets. The binding of LTA to platelets was platelet concentration and time dependent. Binding approached a maximum within 10 min of incubation. The bound LTA could be displaced by adding a 50-fold excess of unlabeled LTA. An association constant of 1.9 X 10(-7) M was calculated, and only one population of binding sites was detected. Immuno-ferritin labeling of LTA-treated platelets demonstrated a patchy distribution of LTA binding sites on the platelet surface. LTA inhibited collagen- and alpha1 chain-induced platelet aggregation, but not the platelet release reaction, suggesting that the LTA and collagen binding sites on human platelets are distinct. Apparently, LTA binds to platelets and interferes with collagen-induced aggregation although collagen is still able to attach to binding sites to trigger the release reaction.

Binding of magnesium ions to cell walls of Bacillus subtilis W23 containing teichoic acid or teichuronic acid

When grown in a chemostat under various nutritional conditions, cells of Bacillus subtilis W23 produce walls containing teichoic acid or teichuronic acid. The binding of Mg2+ to these walls and to the isolated anionic polymers in solution was measured by equilibrium dialysis. In solution the ribitol teichoic acid bound Mg2+ in the molar ratio Mg2+/P=1:1 with an apparent association constant (Kassoc.) of 0.61 X 10(3)M-1, and the teichuronic acid bound Mg2+ in the ratio Mg2+/CO2-=1.1, Kassoc.=0.3 X 10(3)M-1. Cell walls containing teichuronic acid exhibited closely similar binding properties to those containing teichoic acid; in both cases Mg2+ was bound in the ratio Mg/P or Mg/CO2- of 0.5:1 and with a greater affinity than displayed by the isolated polymers in solution. It was concluded that Mg2+ ions are bound bivalently between anionic centres in the walls and that the incorporation of teichoic acid or teichuronic acid into the walls gives rise to similar ion-binding and charged properties. The results are discussed in relation to the possible functions of anionic polymers in cell walls.

Relationship of capsular type to biochemical and immunological properties of teichoic acid preparations from unencapsulated strains of Staphylococcus aureus

We investigated the biochemical and immunological characteristics of teichoic acid preparations (TAP) obtained from four unencapsulated strains of Staphylococcus aureus which nonetheless, according to the serum-soft agar technique, produced capsular type antigen and were representative of the four types A, B, C, and D. In the agar diffusion test, TAP of each strain produced a single precipitin line only against rabbit antisera corresponding to the homologous capsular type; no lines were observed against antisera to the heterologous capsular type. All TAP were ribitol type except one, glycerol, prepared from a capsular type D strain. Major acetylglucosaminyl residues of TAP from strains having capsular type A and C antigens were attached to the polyribitol phosphate by beta-linkage, whereas TAP from a type B antigen strain had an alpha-linkage; type D antigen was attached to the polyglycerol phosphate by the beta-linkage. Chemical analyses and infrared spectrograms of these TAP further confirmed their heterogeneous nature.

Selective adsorption of heterophile polyglycerophosphate antigen from antigen extracts of Streptococcus mutans and other gram-positive bacteria

Hot saline extracts of Streptococcus mutans have been shown to contain antigenic substances which occasionally react nonspecifically with some antisera against whole cells of various serological groups and types of streptococci. Chromatography of the extract of S. mutans strain MT703 (serotype e) on a diethylaminoethyl-Sephadex A-25 column gave two principal antigens. One antigen was eluted without adsorption to the resin and was identified as the serotype-specific polysaccharide. The other antigen, which contained a large quantity of phosphorus, was absorbed to and released from the resin by gradient elution. It was reactive against the antisera specific for polyglycerophosphate (PGP) from group A Streptococcus pyogenes and/or S. mutans strain Ingbritt (type c). The PGP antigen was further purified by gel filtration with Sephadex G-75. Two peaks, PGP-1, and PGP-2, were obtained. Each possessed the same antigenic specificity to anti-PGP serum as shown by immunodiffusion. Chemical analyses revealed that the molar ratio of phosphorus to glycerol in both was about 1:1, although the protein content between the two was significantly different. PGP antigen was found to be widely distributed in hot saline extracts from various gram-positive bacteria, with a few exceptions. However, all gram-negative bacteria examined were free of PGP. The PGP in the hot saline extracts of various gram-positive bacteria possessed an essentially identical antigenic specificity. The addition of diethylaminoethyl-Sephadex A-25 resin to hot saline extracts successfully removed the cross-reacting PGP antigen. After adsorption of the extract from S. mutans, the supernatant contained only type-specific polysaccharide antigen, except type b, in which both type b-specific polysaccharide and PGP antigens were absorbed with the resin. This simple procedure should be useful for the removal of the PGP-type teichoic acid from antigen extracts of bacteria that contain uncharged polysaccharides.

Membrane lipoteichoic acid of Streptococcus pyogenes and its stabilized L-form and the effect of two antibiotics upon its cellular content

Membrane lipoteichoic acid continues to be synthesized by an osmotically fragile, stabilized L-form of Streptococcus pyogenes. Chromatographic and electrophoretic comparisons indicate that the lipid componenent of lipoteichoic acid in this L-form and its parental streptococcus is glycerophosphoryldiglucosyl diglyceride and not phosphatidylkojibiosyl diglyceride. Based upon dry weight determinations, the yield of lipoteichoic acid from the L-form is 0.19%, as compared with 0.97% from the streptococcus. When grown with bacitracin the L-form contains the same amount of teichoic acid as when grown without this antibiotic; however, its lipoteichoic acid content is reduced by 85%. Similarly, the L-form grown with novobiocin for 10 h contains only 17% of the teichoic acid found in control cells.

Defective synthesis of lipid intermediates for peptidoglycan formation in a stabilized L-form of Streptococcus pyogenes

Membrane preparations obtained from a stabilized L-form of Streptococcus pyogenes are incapable of synthesizing peptidoglycan from uridine-5'-diphospho-N-acetyl-D-muramyl-L-Ala-D-iso-Glu-L-Lys-D-Ala-D-Ala and uridine-5'-diphospho-N-acetyl-D-glucosamine, in contrast with similar preparations from the parental streptococcus. Furthermore, 50-fold higher levels of lipid intermediates which serve as membrane-bound substrates for peptidoglycan synthesis are synthesized in reaction mixtures containing streptococcal membranes than with similar preparations from the L-form. These observations suggest that the inability of this stabilized L-form to form a cell wall in vivo lies, at least in part, in its failure to synthesize significant quantities of the lipid substrates for peptidoglycan synthesis.

Membrane studies of Streptococcus pyogenes and its L-form growing in hypertonic and physiologically isotonic media. An electron spin resonance spectroscopy approach

Electron spin resonance spectroscopy (ESR) was used to compare the lipid organization, thermal stability and the physical state of the membrane of a human pathogen, Streptococcus pyogenes and its osmotically fragile L-form with this same L-form now adapted to grow under physiologically isotonic conditions (physiological L-form). Comparison of the hyperfine splittings of a derivative of 5-ketostearic acid spin label, I(12, 3), after incorporation into the membrane, revealed that the lipid chain rigidity of these membranes is in the order physiological L-form greater than osmotically fragile L-form greater than streptococcus. The signal intensity (of the center magnetic field line) versus temperature analysis showed two transitions for these membranes. The first with melting points of 45, 26 and 36 degrees C and second transition at 70, 63 and 60 degrees C for the physiological L-form, osmotically fragile L-form and streptococcal membranes, respectively. This same order of membrane lipid chain rigidity was seen from the cooperativities obtained for each of these systems from analysis based on the expression for an n-order reaction. The I(12, 3) and other probes with the paramagnetic group close to the methyl end of the molecule suggested that this difference in lipid chain rigidity between these organisms resides in the environment closer to the lipid head group region rather than in the hydrophobic lipid core. Another major finding was the binding of I(12, 3) at two or more different sites in each of the membranes examined. This change in lipid chain rigidity now provides an explanation to account for the survival of a previously osmotically fragile L-form in physiologically isotonic media by focusing on changes in the physical nature of its membrane. In so doing, it adds to and reinforces the speculation of the potential survival in vivo and involvement in pathogenesis of osmotically fragile aberrant forms of bacteria.

Influence of alanyl ester residues on the binding of magnesium ions to teichoic acids

The binding of Mg2+ to the ribitol teichoic acid of Staphylococcus aureus H walls was examined by equilibrium dialysis in solution and in the intact wall; the influence of alanyl ester groups on binding was determined. In solution the ribitol polymer had a lower affinity than did a glycerol teichoic acid and bound Mg2+ in the ratio Mg2+/P of 1:1. The presence of alanyl ester residues caused a decrease in the amount of cations bound in stoicheiometric proportion to the ratio Ala/P, but the affinity constant was unaltered. It is concluded that in solution the ribitol teichoic acid binds Mg2+ univalently to phosphate groups and univalently to a counter-ion. In the intact wall the binding of Mg2+ was different. The affinity constant was higher and resembled that of a glycerol teichoic acid. It is concluded that Mg2+ forms bridges across phosphate groups in teichoic acid chains lying adjacent to each other in the wall. The effect of alanyl esters was similar to that in solution, but Scatchard plots were not linear at low concentrations of Mg2+ where it was shown that the difference in affinities between walls with and without alanyl ester residues was much greater than it was at higher concentrations of Mg2+. Thus at very low concentrations of Mg2+ effective binding to the wall is markedly improved by loss of alanyl ester residues.

The interaction of magnesium ions with teichoic acid

The binding of Mg2+ to the wall teichoic acid of Lactobacillus buchneri N.C.I.B. 8007 was measured by equilibrium dialysis at controlled ionic concentration and pH. In an aqueous solution containing 10mM-NaCl at pH 5.0 one Mg2+ ion was bound for every two phosphate groups of the teichoic acid, with an apparent association constant, Kassoc. = 2.7 x 10(3) M-1. On lowering the pH below the pKa of the phosphate groups the amount of bound Mg2+ decreased concomitantly with decreasing ionization of the phosphate groups. Both the amount of Mg2+ bound to the teichoic acid and the apparent association constants were similar in the presence of 10 mM concentrations of NaCl or KCl but decreased markedly in the presence of 10 mM-CaCl2 because of competition between Ca2+ and Mg2+ for the binding sites. A similar effect was found when the concentration of NaCl was increased from 0 to 50 mM. The results are discussed in relation to the function of teichoic acid in the walls of Gram-positive bacteria.

Extraction and purification of lipoteichoic acids from Gram-positive bacteria

Hot and cold, 80% aqueous phenol extraction procedures together with an aqueous extraction technique have been evaluated for the isolation of lipoteichoic acids from the cytoplasmic membrane of Gram-positive bacteria. Lipoteichoic acids of Staphlococcus aureus H, Micrococcus 2102, Baccillus subtilis 168, and Bacillus subtilis W-23 were examined as each of them emphasises a different problem of contamination. The purity of the lipoteichoic acids with respect to cell-wall material, nucleic acid, and protein is discussed together with the criteria of purity which enables critical structural analysis of lipoteichoic acids to be carried out.

Incorporation of D-alanine into the membrane of Streptococcus pyogenes and its stabilized L-form

A principal aim of this study was to explain our earlier finding of a lack of d-alanine in the glycerol teichoic acid from the membrane of a stabilized L-form of Streptococcus pyogenes (B. M. Slabyj and C. Panos, 1973. J. Bacteriol. 114:934-942). It was found that the incorporation of d-alanine into the membrane teichoic acid of S. pyogenes requires either supernatant fraction or two enzymes from supernatant fraction, stimulator (d-alanine activating enzyme) and d-alanine:membrane acceptor ligase, plus membrane fragments, ATP and Mg(2+). A similar system from the L-form is inoperative. Also, no incorporation is observed with L-form or coccal supernatant fractions when L-form membranes are used. However, d-alanine incorporation is observed when L-form enzymes are used with membrane fragments from the parental streptococcus. Thus, the L-form possesses the required soluble components for d-alanine incorporation but the L-form membrane cannot function as acceptor even though it contains d-alanine-deficient membrane teichoic acid. These results suggest that a defect has occurred in the membrane of this stabilized L-form for d-alanine incorporation into membrane teichoic acid.

Lipoteichoic acid localization in mesosomal vesicles of Staphylococcus aureus

Mesosomal vesicles and plasma membranes of Staphylococcus aureus ATCC 6538P have been prepared and examined for the presence of lipoteichoic acid. Lipids were first removed by treatment with pyridine-acetic acid-butanol (22:31:100, vol/vol/vol) and chloroform-methanol (2:1, vol/vol). Subsequently, lipoteichoic acid was removed with 40% phenol in water. The lipoteichoic acid from mesosomal vesicles was characterized by (i) equimolar glycerol and phosphate, (ii) alanine upon hydrolysis (2 N NH(4)OH, 18 h, 22 C), and (iii) fatty acids, diglycerol triphosphate, glycerol monophosphate, and glycerol diphosphate upon alkaline hydrolysis (1 N NaOH, 3h, 100 C). The plasma membranes contained no lipoteichoic acid. The presence in mesosomal vesicles of 18% of the dry weight as lipoteichoic acid and its absence from plasma membranes provide the first major chemical differences between these organelles. A study of the lipoteichoic acid content in various fractions of the cell showed that the mesosomal vesicles were the major and probably the sole site for the localization of the lipoteichoic acid in these organisms. A new method for the preparation of mesosomes in increased yields is reported. A theory for the control of cell division involving lipoteichoic acid and the mesosome is proposed.

Antigens of Streptococcus mutans. II. Characterization of an antigen resembling a glycerol teichoic acid in walls of strain BHT

Cold 10% trichloroacetic acid was used to extract antigens from purified cell walls of Streptococcus mutans BHT. Column chromatography on Biogel P-100 resolved two serologically reactive fractions (B and C). These fractions were ascertained to be relatively pure by recycling on Biogel P-100, Ouchterlony double-diffusion analysis, and immunoelectrophoresis. Fractions B and C demonstrated bands of absolute homology by double-diffusion but different mobilities by immunoelectrophoresis. Chemical analysis indicated that fraction B is a polysaccharide composed principally of rhamnose and galactose, with smaller amounts of glucose and glucosamine. Small quantities of glycerol and phosphorus also were found. Fraction C was composed mainly of galactose, glycerol, and phosphorus. Alkaline hydrolysis of this fraction yielded products typically released by the degradation of a glycerol teichoic acid, such as glycerol monophosphate, glycerol diphosphate, inorganic phosphorus, and several glycosyl glycerol phosphates. Diglycerol triphosphate was not detected. Side-group analysis revealed that glycerol was substituted by mono- and trigalactosyl moieties. Fraction C was deduced to contain 25 glycerol phosphate units per polymer length. Hapten inhibition studies revealed a beta-galactoside as the probable hapten on this antigen. The BHT teichoic acid reacted strongly with FA-1 antiserum. It showed bands of homology with both BHT and FA-1 crude acid extracts upon double-diffusion, using antisera to either strain. The BHT teichoic acid also displayed immunoelectrophoretic behavior identical to one of the mobile FA-1 cell wall antigens, again using either serum to develop precipitin bands. It is concluded this antigen may possess a serotype-specific determinant for S. mutans serotype b.