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PubMed1980

[Reciprocal in vitro actions of Streptococcus mutans, Actinomyces and Veillonella: a simplified model for carbohydrate metabolism in plaque].

Different acids can be found in vitro, if glucose is metabolized in plaque or by different combinations or oral bacteria: 1. Streptococcus mutans and Actinomyces do not show interactions concerning metabolism and formed acids. 2. Streptococcus mutans and Veillonella after short incubation time produce lactate; after long time of incubation acetic and propionic acid are main products and lactic acid diminishes. 3. Actinomyces and Veillonella react similar to Streptococcus mutans and Veillonella. Succinate produced by Actinomyces is fully utilized by Veillonella.

Actinomyces↗

PubMed1987

Structural studies of the serotype-f polysaccharide antigen from Streptococcus mutans OMZ175.

The serotype f antigen of Streptococcus mutans has been described as a rhamnose-glucose polysaccharide associated with the bacterial cell wall. In this study, the structure of serotype f polysaccharide was examined by analyses of the methylated derivatives of the antigen and the periodate-oxidized antigen. Methylated derivatives were characterized with a gas chromatograph-mass spectrometer. The polysaccharide appeared to have a backbone of alternating 1,3- and 1,2,3-linked rhamnose units. Branching occurred at the 3-position of the 1,2,3-linked rhamnose. Side chains were composed of terminal alpha-linked glucose units. A small proportion of longer side chains containing 1,2- and 1,6-linked glucose units were noted in some preparations; however, these determinants were not reactive with serotype f antisera.

Antigens, Bacterial↗

PubMed1976

Susceptibility of Streptococcus mutans to antimicrobial agents.

Fifty strains of Streptococcus mutans, including defined strains and clinical isolates, were tested for susceptibility to 20 different antimicrobial agents. Minimal inhibitory concentrations were determined by a liquid microtiter procedure. Antibiotics that were most effective in concentrations below 0.1 mug/ml included penicillin, ampicillin, erythromycin, cephalothin, and methicillin. Antibiotics effective in concentrations between 0.1 mug and 10 mug/ml included rifampin, lincomycin, thiostrepton, spiromycin, vancomycin, streptolydigan, novobiocin, tetracycline, chloramphenicol, spectinomycin, and gentamicin. Antibiotics effective at higher concentrations ranging from 10 mug/ml to 400 mug/ml included the aminoglycosides kanamycin, neomycin, streptomycin, and kasugamycin. Although most antibiotics exhibited inhibitory effects in a narrow range of concentrations, antibiotics such as tetracycline, thiostrepton, and spiromycin had a 1,000-fold range from the lowest to highest concentrations required for growth inhibition.

Anti-Bacterial Agents↗

PubMed1983

Characterization of a salivary agglutinin reacting with a serotype c strain of Streptococcus mutans.

A protein, which can agglutinate a Streptococcus mutans serotype c strain, was isolated from parotid saliva by affinity adsorption of the salivary agglutinin to the microorganism followed by a desorption with a 10 mM phosphate buffer. The agglutinin was subjected to preparative ultracentrifugation, gel filtration, and ultrafiltration. The native purified agglutinin is active only in the presence of Ca. Polyacrylamide gel electrophoresis, analytical centrifugation, and analyses of amino acids and carbohydrates showed that the native agglutinin was a fucose-rich glycoprotein with a carbohydrate content of 45% and with a molecular weight of at least 5 X 10(6). After sodium dodecyl sulphate treatment the molecular weight was 4.4 X 10(5). There was a low content of proline and a high content of aspartic acid, serine and threonine. The concentration of agglutinin in parotid saliva is less than 0.5% of total protein. It has high biological activity: 0.1 microgram agglutinin causes a rapid aggregation of approximately 10(8) bacteria.

Agglutination Tests↗

PubMed1988

Adhesion of Streptococcus rattus and Streptococcus mutans to metal surfaces.

The adhesion of Streptococcus rattus BHT and Streptococcus mutans IB to metal specimens of amalgam, silver, tin and copper was studied using (6-3H)thymidine labeled cells. In the standard assay the metal specimens were suspended by a nylon thread in an adhesion solution containing a chemically defined bacterial growth medium (FMC), sucrose, and radiolabeled bacteria. Maximum amounts of adhering bacteria were obtained after about 100 min of incubation. Saturation of the metal specimens with bacteria was not observed. Both strains also adhered in the absence of sucrose, indicating that glucan formation was not necessary for adhesion. However, in the presence of glucose, adhesion was only 26-45% of that observed in the presence of equimolar sucrose. Sucrose-dependent stimulation of adhesion seemed to be due to increased cell-to-cell adhesion capacity. Isolated radiolabeled water-insoluble and water-soluble polysaccharides produced from sucrose by S. rattus BHT were not adsorbed to the metal surfaces.

Absorption↗

PubMed1995

Purification and characterization of Streptococcus mutans glucosyltransferase (GtfC) expressed in Escherichia coli.

Streptococcus mutans constitutively expresses three glucosyltransferases, i.e., GtfB, GtfC, and GtfD; which synthesize glucan polymers from sucrose. To obtain individual GTF without complexing with one another, a purification strategy was developed to recover recombinant GTF expressed from Escherichia coli. The recombinant GtfC was aggregated and associated with the insoluble fraction in E. coli homogenates. GtfC was solublized with the 8M urea, renatured to its biologically active form by serial dialysis against sodium phosphate buffer, and subsequently purified to homogeneity by DEAE-Sephacel and hydroxylapatite column chromatography. The GtfC enzyme preparation was purified 16.3-fold and the molecular weight was estimated to be 140 kDa. GtfC synthesized water insoluble glucan in a primer independent manner and its enzymatic activities could be enhanced by dextran. Purified GtfC had a pH optimum of 6.5, a K(m) of 9.26 mM for sucrose and a pI of 5.5. Distinct from the previous reports, results from this study offers an alternative for the purification of the recombinant GTFs free from any detergent contamination to make it more suitable for utilization in vivo.

Escherichia coli↗

PubMed2004

Production of functional ScFv inhibiting Streptococcus mutans glucosyltransferase activity from a hybridoma P126.

Streptococcus mutans has been considered the principal etiologic agent of dental caries in humans. The glucosyltransferase-I (GTF-I), which synthesized adhesive water-insoluble glucans from sucrose, has been demonstrated to be an important cariogenic property. Water-insoluble glucans (WIG) synthesized by S. mutans GTF-I can mediate sucrose-enhanced colonization on tooth surfaces and form dental plaque. It has been suggested that inhibition of WIG synthesis decreases bacterial colonization and cariogenicity. Indeed, the use of GTF enzymes as a vaccine antigen resulted in protection from experimental dental caries in rodents. However, it is preferable to eliminate unwanted immune response during active immunization of humans. To prevent this incidence, we attempted to produce the single-chain variable fragment (ScFv) antibody against GTF-I to develop passive immunization for dental caries. Hybridomas producing monoclonal antibody (MAb) that inhibited WIG synthesis by GTF-I have been constructed. Using mRNA from an IgG1 hybridoma P126, cDNAs encoding the variable fragments of the L and H chains of IgG1 from the hybridoma P126 were cloned by RT-PCR-based techniques and then transformed into an Escherichia coli expression system. The purified ScFv antibody recognized the recombinant (r) GTF-I proteins and was capable of inhibiting the WIG synthesis of rGTF-I.

Binding Sites↗

PubMed1989

Characterization of a cell-surface protein antigen of hydrophilic Streptococcus mutans strain GS-5.

Fourteen strains of Streptococcus mutans serotype c were examined for their cell-surface protein antigens in terms of hydrophobicity, Mr and immunochemical specificities. Thirteen strains were hydrophobic, while strain GS-5 was markedly hydrophilic as compared to the other strains tested. Cell-surface protein antigens were then analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western immunoblotting. A protein antigen of Mr 190,000 (PAc) was found in cell extracts and culture supernatants of all the hydrophobic strains. Neither culture supernatant nor cell extract of strain GS-5 contained PAc. Strain GS-5, however, produced extracellularly a large amount of a protein of Mr 155,000 (PAGS-5) which reacted with rabbit anti-PAc serum. Immunodiffusion analysis showed that PAGS-5 lacked a part of the antigenic moieties in the PAc molecule. SDS-PAGE and radioimmunoassay showed a small amount of PAGS-5 on the cell surface of strain GS-5. These findings suggest that PAGS-5 may correspond to PAc which lacks a region participating in binding of PAc to the streptococcal cell.

Antigens, Bacterial↗

PubMed1977

Purification, resolution, and interaction of the glucosyltransferases of Streptococcus mutans 6715.

The extracellular glucosyltransferase produced by Streptococcus mutans 6715 was purified from culture supernatant fluids to a specific activity of 9.6 IU/mg of protein, with an overall recovery of 87%. The purified enzyme preparation, designated unfractionated enzyme (UFE), synthesized only water-insoluble glucans from sucrose during the initial stages of the reaction, although some water-soluble polymers accumulated after extended periods of incubation. It was free from measurable fructosyltransferase activity. The UFE preparation was resolved into two different catalytically active components by ethanol fractionation. One fraction (designated insoluble product enzyme [IPE]) synthesized water-insoluble glucans, whereas the other (designated soluble product enzyme [SPE]) produced primarily water-soluble glucans. The difference between the insoluble glucans made by the UFE preparation and those made by the IPE fraction appeared to be due to interaction of the SPE and IPE components in the UFE preparation. Addition of commercial dextrans or enzymatically prepared glucans to the glucosyltransferase assay altered the amounts of soluble and insoluble glucans synthesized by the UFE preparation. The molecular weights of the major enzymatically active proteins producing insoluble and soluble glucans were estimated by gel filtration chromatography to be 150,000 and 175,000, respectively.

Dextranase↗

PubMedDate not supplied

Identification of core B cell epitope in the synthetic peptide inducing cross-inhibiting antibodies to a surface protein antigen of Streptococcus mutans.

A surface protein antigen (PAc) of Streptococcus mutans, in particular, A-region of the molecule, has been considered as a possible target for the development of an effective anticaries vaccine. This region might be implicated in the induction of dental caries via interaction with salivary components. We have recently specified a unique peptide, TYEAALKQYEADL, as one of the minimum peptides that completely corresponds to the amino acid sequence of a part of the A-region. The unique peptide contains both T and B cell epitopes for the induction of cross-reacting antibodies to the PAc. In this study, we synthesized valine or glycine-substituted peptide analogs of this peptide and examined core B cell epitopes of this unique peptide by using ELISA inhibition assay. As a result, the core amino acid residues of -Y------Y---- for B cell recognition were found to likely be not only important amino acids stabilizing the structure, but also might be essential for induction of the cross-inhibiting antibodies against PAc. These results will hopefully provide us with useful information for the design of an effective anticaries peptide vaccine.

Amino Acid Sequence↗

PubMed1978

Aspartokinase of Streptococcus mutans: purification, properties, and regulation.

Aspartokinase from Streptococcus mutans BHT was purified to homogeneity and characterized. The molecular weight of the native enzyme was estimated to be 242,000 by gel filtration. Cross-linking of aspartokinase with dimethyl suberimidate and polyacrylamide gel electrophoresis of the amidinated enzyme in the presence of sodium dodecyl sulfate showed the enzyme to be composed of six identical subunits with a molecular wieght of 40,000. The optimal pH range for enzyme activity was 6.5 to 8.5. The apparent Michaelis-Menten constants for aspartate and ATP were 5.5 and 2.2 mM, respectively. The enzyme was stable within the temperature range of 10 to 35 degrees C. Aspartokinase was not feedback inhibited by individual amino acids, but was concertedly inhibited by L-lysine and L-threonine (93.5% inhibition at 10 mM each). The inhibition was noncompetitive with respect to aspartate (Ki = 10 mM) and mixed with respect to ATP. L-Threonine methyl ester and L-threonine amide were able to substitute for L-threonine in feedback inhibition, but the requirement for L-lysine uas strict. The feedback inhibitor pair protected the enzyme against heat denaturation. Aspartokinase synthesis was repressed by L-threonine; this repression was enhanced by L-lysine, but was slightly attenuated by L-methionine.

Adenosine Triphosphate↗

PubMed2003

Structural analysis of the functional influence of the surface peptide Gtf-P1 on Streptococcus mutans glucosyltransferase C activity.

Glucosyltransferases (GtfB/C/D) in Streptococcus mutans are responsible for synthesizing water-insoluble and water-soluble glucans from sucrose and play very crucial roles in the formation of dental plaque. A monoclonal antibody against a 19-mer peptide fragment named Gtf-P1 was found in GtfC to reduce the enzyme activity to 50%. However, a similar experiment suggested almost unchanged activity in GtfD, despite of the very high sequence homology between the two enzymes. No further details are yet available to elucidate the biochemical mechanism responsible for such discrimination. For a better understanding of the catalytic behavior of these glucosyltransferases, structural and functional analyses were performed. First, the exact epitope was identified to specify the residue(s) required for monoclonal antibody recognition. The results suggest that the discrimination is determined solely by single residue substitution. Second, based on a combined sequence and secondary structure alignment against known crystal structure of segments from closely related proteins, a three-dimensional homology model for GtfC was built. Structural analysis for the region communicating between Gtf-P1 and the catalytic triad revealed the possibility for an "en bloc" movement of hydrophobic residues, which may transduce the functional influence on enzyme activity from the surface of molecule into the proximity of the active site. Figure Side chain interactions between Gtf-P1 and catalytic Asp-477 in GtfC. Calpha-tracing of GtfC with the two crucial peptides (Gtf-P1, orange; Gtf-P2, blue) and the catalytic triad residues ( red) highlighted to show their relative spatial organization. Side chains for the residues are also depicted according to their atom types. The structure is viewed with the barrel opening facing down

Amino Acid Sequence↗

PubMed1980

Inhibition of peptidoglycan, ribonucleic acid, and protein synthesis in tolerant strains of Streptococcus mutans.

Exposure of exponentially growing cultures of Streptococcus mutans strains FA-1 and GS-5 to various concentrations of benzylpenicillin (Pen G) resulted in inhibition of turbidity increases at low concentrations (0.02 to 0.04 mug/ml). However, in contrast to some other streptococcal species, growth inhibition was not accompanied by cellular lysis or by a rapid loss of viability. In both strains, synthesis of insoluble cell wall peptidoglycan was very sensitive to Pen G inhibition and responded in a dose-dependent manner to concentrations of about 0.2 and 0.5 mug/ml for strains GS-5 and FA-1, respectively. Higher Pen G concentrations failed to inhibit further either growth or insoluble peptidoglycan assembly. Somewhat surprisingly, Pen G also inhibited both ribonucleic acid (RNA) and protein syntheses, each in a dose-dependent manner. Compared with inhibition of peptidoglycan synthesis, inhibition of RNA and protein syntheses by Pen G was less rapid and less extensive. Maximum amounts of radiolabeled Pen G were specifically bound to intact cells upon exposure to about 0.2 and 0.5 mug/ml of Pen G for strains GS-5 and FA-1, respectively, concentrations consistent with those that resulted in maximum or near-maximum inhibitions of the synthesis of cellular peptidoglycan, RNA, and protein. Five polypeptide bands that had a very high affinity for [(14)C]Pen G were detected in a crude cell envelope preparation of strain FA-1. After exposure of cultures of strain FA-1 to the effects of saturating concentrations of the drug for up to 3 h, addition of penicillinase was followed by recovery of growth after a lag. The length of the lag before regrowth depended on both Pen G concentration and time of exposure. On the basis of these and other observations, it is proposed that the secondary inhibitions of cellular RNA or protein synthesis, or both, are involved in the tolerance of these organisms to lysis and killing by Pen G and other inhibitors of insoluble peptidoglycan assembly.

Autolysis↗

PubMed1989

Growth and adsorption of Streptococcus mutans 6715-13 to hydroxyapatite in the presence of lactoferrin.

The growth of Streptococcus mutans 6715-13 in a rich medium (Todd Hewitt broth) was drastically reduced by addition of apo-lactoferrin (apo-Lf); this effect was bacteriostatic and reversible by saturation of Lf with iron. The influence of Lf, salivary proteins (SP) and bovine serum albumin (BSA) on the attachment of Streptococcus mutans to hydroxyapatite (HA) was successively investigated. Sorption of Lf, SP, and BSA to HA was dependent on the protein concentration and reached the end-point at about 80 mg of proteins per gram of HA. Similarly, the number of streptococci adsorbed to HA was correlated to the amount of cells available up to at least 10(7) cells per mg of HA. The adsorption of Lf, SP and BSA on HA reduced the number of attaching S. mutans cells. In particular, SP reduced the adsorption of S. mutans by 30%, whereas pre-coating of HA with apo- or iron-saturated Lf resulted in a three orders of magnitude reduction of S. mutans adsorption to HA, as demonstrated by means of different experimental procedures. The powerful adherence-inhibiting effect of apo-Lf together with its noticeable antibacterial activity towards S. mutans points to a biological significance of these phenomena also in vivo.

Adsorption↗

PubMed1993

Sucrose-derived exopolysaccharides of Streptococcus mutans V403 contribute to infectivity in endocarditis.

We used an isogenic mutant of Streptococcus mutans V403, which differs from the wild-type V403 in genes involved in glucan and fructan production, to examine the importance of these exopolysaccharides as factors affecting infectivity in endocarditis. Rats inoculated with V403 developed endocarditis more frequently than animals inoculated with the mutant strain which produced neither glucan nor fructan (58% versus 12%, P < 0.01). In phagocytosis assays, both strains were found to be associated with the human granulocytes but a greater number of live V403 than of mutant organisms could be recovered. Colony counts recovered from fibrin plates incubated with the mutant were lower than those incubated with V403. These experiments indicate that exopolysaccharides produced by Streptococcus mutans contribute to its infectivity in endocarditis.

Alleles↗

PubMed1978

Co-induction of beta-galactosidase and the lactose-P-enolpyruvate phosphotransferase system in Streptococcus salivarius and Streptococcus mutans.

The addition of lactose, galactose, or isopropyl-beta-D-thiogalactoside (IPTG) to glucose-grown cells of Streptococcus salivarius 25975 resulted in the co-induction of both the lactose-P-enolpyruvate phosphotransferase system (lactose-PTS) and beta-galactosidase, with the latter the predominant metabolic system. With various strains of Streptococcus mutans and Streptococcus sanguis 10556, on the other hand, the lactose-PTS was the major metabolic pathway with beta-galactosidase induced either to low or negligible levels. In all cases, induction of the lactose-PTS resulted in the concomitant induction of 6-P-beta-galactosidase. The induction by lactose of both the lactose-PTS and beta-galactosidase in all strains was repressed by glucose and other catabolites, notably, fructose. Induction of beta-galactosidase in S. salivarius 25975 by IPTG was, however, relatively resistant to glucose repression. Induction experiments with IPTG and lactose suggested that a cellular metabolite of lactose metabolism was a repressor of enzyme activity. Exogenous cAMP was shown to reverse the transient repression by glucose of beta-galactosidase induction in cells of S. salivarius 25975 receiving lactose, provided the cells were grown with small amounts of toluene to overcome the permeability barrier to this nucleotide, cAMP, was however, unable to overcome the permanent repression of beta-galactosidase activity to a significant extent under these conditions.

Cyclic AMP↗

PubMed1996

Role of the C terminus in antigen P1 surface localization in Streptococcus mutans and two related cocci.

The C terminus of the major surface protein P1 from Streptococcus mutans is composed of a hydrophilic domain, an LPNTGV motif, a hydrophobic domain, and a charged tail. These features are shared by surface proteins from many gram-positive coccal bacteria. To investigate the role of the C-terminal domains in antigen P1 surface localization, full-length and truncated P1 gene constructs, which were expressed on the shuttle vector pDL276, were transformed into the P1-negative mutant S. mutans SM3352, Streptococcus gordonii DL-1, and Enterococcus faecalis UV202. Transformants were tested for expression of P1 by enzyme-linked immunosorbent assaying and Western blotting. The results showed that full-length P1 was expressed by transformants of all three bacteria and was localized on the cell surface. A fusion protein composed of the Staphylococcus aureus fibronectin binding protein C terminus and the P1 protein N terminus was found to surface localize in S. mutans. Deletion of the entire C-terminal domains resulted in P1 being expressed in the culture supernatant. A P1 truncation, which carried only the hydrophilic domain at its C terminus, was found partially associated with the cell surface. This truncated P1 was readily removed from the isolated cell wall by hot sodium dodecyl sulfate-mercaptoethanol extraction. In contrast, the full-length P1 remained associated with the isolated cell wall after similar treatment, suggesting covalent linkages between the full-length P1 and the cell wall. The results described above showed that antigen P1 was anchored to the cell wall by its C-terminal domains probably via covalent linkages with the cell wall. The results also support a universal mechanism involving the C-terminal domains for protein surface localization among this group of gram-positive bacteria.

Amino Acid Sequence↗

PubMedDate not supplied

Streptococcus mutans genotypes isolated from root and coronal caries.

The aim of the present study was to evaluate the colonization profile and clonal distribution of Streptococcus mutans isolated from oral cavities that presented coronal and root caries lesions. The isolation and biochemical identification of mutans streptococci were carried out by using saliva samples, dental plaque, and tissue from the caries lesions. In order to confirm their molecular identity, S. mutans and Streptococcus sobrinus were submitted to the PCR method, using specific primers for portions of the glucosyltransferase genes (gtfB and gtfI, respectively). The AP-PCR method was used to detect the genetic polymorphism of S. mutans strains. Among the isolated and identified species, S. mutans showed a significantly greater frequency of isolation (59.2%) than the other mutans streptococci. Each of the subjects harbored two to ten genotypes of S. mutans, randomly distributed in different sites. S. mutans genotypes showed no evidence of variability in colonizing noncarious and carious surfaces within the same individual, nor evidence of etiologic differences between coronal and root caries. This study showed that no particular genotype of S. mutans is uniquely associated with the initiation and progression of caries, and that root and coronal caries can emerge in the presence of a broad spectrum of S. mutans clones.

Aged↗