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PubMed1993

Identification of a salivary agglutinin-binding domain within cell surface adhesin P1 of Streptococcus mutans.

DNA encoding the alanine-rich region (A-region) of the cell surface adhesin, P1, from Streptococcus mutans was subcloned and expressed as a fusion protein with the maltose-binding protein (MBP) of Escherichia coli. The A-region fusion protein was shown to competitively inhibit both adherence of S. mutans to salivary agglutinin-coated hydroxyapatite and fluid-phase agglutinin-mediated aggregation of this organism. MBP alone or an MBP-paramyosin fusion protein was not inhibitory. Proteolytic cleavage of the fusion protein into its component moieties, MBP and A-region, resulted in breakdown of the A-region into three main fragments. Western immunoblot analysis of calcium-dependent agglutinin binding to this preparation revealed binding specificity for a 28-kDa fragment. Thus, the A-region of P1 is an important domain which interacts directly with salivary agglutinin, and this interaction interferes with both the aggregation and the adherence mechanisms in vitro.

Adhesins, Bacterial↗

PubMed1977

The amino acid composition of Streptococcus mutans and its culture medium supplemented with xylitol.

The amino and keto acid composition of the cells of Streptococcus mutans, strain Ingbritt, maintained and grown on a Trypticase-Phytone based medium without any added carbohydrate or supplemented with xylitol or glucose, was analyzed. The results showed no remarkable differences in the portions of individual amino acids liberated by acid hydrolysis from the cellular proteins of cells grown in the above mentioned media. However, the amount of free amino acids in the water extracts of the cells grown in the glucose medium differed considerably from those obtained from cells grown in the two other media. The amounts of free amino acids of the medium at the end of the growth period were higher in the glucose containing medium than in the two other media. The content of keto acids was lower in the cells grown in the presence of xylitol or without added carbohydrate when compared to those cells grown in glucose containing medium.

Amino Acids↗

PubMed1987

ATP-dependent protein kinase activities in the oral pathogen Streptococcus mutans.

ATP-dependent protein kinase activities were detected in both membrane and cytoplasmic fractions from the oral pathogen Streptococcus mutans. Different polypeptides were phosphorylated by endogenous kinase(s) in the two fractions. In membranes, five phosphoproteins were detected with apparent masses of 82, 37, 22, 12, and 10 kilodaltons (KD). In cytoplasm, two major acid-stable phosphoproteins were found. One was identified as HPr of the phosphoenolpyruvate (PEP)-dependent phosphotransferase system (PTS), while the other had an apparent mass of 61 KD. Both of these proteins were phosphorylated on a seryl residue. Fructose 1,6-bisphosphate stimulated phosphorylation of HPr by the kinase and inhibited phosphorylation of the 61-KD protein. In contrast, fructose 1-phosphate, 2-phosphoglycerate, 3-phosphoglycerate, and dihydroxyacetone phosphate inhibited phosphorylation of HPr and stimulated phosphorylation of the 61-KD protein. Several other glycolytic intermediates as well as inorganic phosphate inhibited phosphorylation of either or both proteins. Preincubation of cytoplasm with PEP prior to incubation with ATP reduced the amount of phospho-(seryl)-HPr formed, but not that of the 61-KD phosphoprotein. The latter protein has not yet been identified but has properties that suggest that it may be the protein kinase itself. These results provide evidence for one or more soluble ATP-dependent protein kinases in S mutans that are regulated by glycolytic intermediates and that may play a role in the modulation of carbohydrate uptake and metabolism in this organism. A model for feedback regulation of sugar transport in S mutans, mediated by an allosterically regulated kinase, is presented.

Bacterial Proteins↗

PubMed1980

Purification and characterization of a rhamnose-containing cell wall antigen of Streptococcus mutans B13 (serotype d).

A rhamnose-containing polysaccharide (RCP) was extracted and purified from cell walls of Streptococcus mutans B13 (serotype d) and was chemically and immunologically characterized. Walls were initially extracted with 5% trichloroacetic acid at 4 degrees C to remove the serotype antigen and were then sequentially extracted with increasing concentrations of hot acid. Extracts lacking galactose were combined and chromatographed on a column of diethylaminoethyl--Sephadex A25. The purified RCP contained 90% carbohydrate, 1.4% protein, and 0.16% phosphorus. Analysis by gas chromatography indicated that the RCP was composed of rhamnose and glucose in a 1.6:1 ratio. RCP was immunogenic in rabbits when animals were immunized with whole cells or cell walls. Antisera prepared against partially extracted cell walls of B13 appeared specific for RCP. These sera were not reactive with purified serotype d antigen or lipoteichoic acid in passive hemagglutination assays or by agar gel diffusion. The RCP appeared to be a cell wall polysaccharide that was both chemically and immunologically distinct from the serotype d antigen.

Animals↗

PubMed2004

An ffh mutant of Streptococcus mutans is viable and able to physiologically adapt to low pH in continuous culture.

Previously, we described in Streptococcus mutans strain NG8 a 5-gene operon (sat) that includes ffh, the bacterial homologue of the eukaryotic signal recognition particle (SRP) protein, SR54. A mutation in ffh resulted in acid sensitivity but not loss of viability. In the present study, chemostat-grown cells of the ffh mutant were shown to possess only 26% and 39% of the parental membrane F-ATPase activity and 55% and 75% of parental glucose-phosphotransferase (PTS) activity when pH-7 and pH-5-grown cells, respectively, were assayed. Two-dimensional-gel electrophoretic analyses revealed significant differences in protein profiles between parent and ffh-mutant strains at both pH 5 and pH 7. It appears that the loss of active SRP (Ffh) function, while not lethal, results in substantial alterations in cellular physiology that includes acid tolerance.

Acclimatization↗

PubMed1979

Chemical, immunochemical, and structural studies of the cross-reactive antigens of Streptococcus mutans AHT and B13.

Two antigenic polysaccharides were extracted from cell walls of the cross-reactive strains Streptococcus mutans AHT (a) and S. mutans B13 (d). The antigens extracted from walls by the hot formamide method, were purified by affinity chromatography on columns containing the galactose-specific lectin from the castor bean and were found to be diheteroglycans consisting of galactose and glucose. Antigenic specificities of both the serotype-specific and the cross-reactive sites on each polymer were studied: the AHT (a) antigen is determined by D-galactose linked 1 leads to 6 to adjacent sugar, the B13 (d) antigen is determined by D-glucose similarly linked to o its neighbor, and the cross-reactive (a--d) site present on both polymers consists of D-galactose linked 1 leads to 6 to a subterminal sugar moiety. Methylation analysis revealed structural similarities between the purified polysaccharides that may reflect the nature of the cross-reactive sites and differences that may reflect the natures of the specific haptenic regions. Based on these studies, a partial hypothetical structural model is proposed.

Antigens, Bacterial↗

PubMed2004

Characterization of the Streptococcus mutans P1 epitope recognized by immunomodulatory monoclonal antibody 6-11A.

Monoclonal antibody (MAb) 6-11A directed against Streptococcus mutans surface adhesin P1 was shown previously to influence the mucosal immunogenicity of this organism in BALB/c mice. The specificity of anti-P1 serum immunoglobulin G (IgG) and secretory IgA antibodies and the subclass distribution of anti-P1 serum IgG antibodies were altered, and the ability of elicited serum antibodies to inhibit S. mutans adherence in vitro was in certain cases increased. MAb 6-11A is known to recognize an epitope dependent on the presence of the proline-rich region of the protein, although it does not bind directly to the isolated P-region domain. In this report, we show that MAb 6-11A recognizes a complex discontinuous epitope that requires the simultaneous presence of the alanine-rich repeat domain (A-region) and the P-region. Formation of the core epitope requires the interaction of these segments of P1. Residues amino terminal to the A-region also contributed to recognition by MAb 6-11A but were not essential for binding. Characterization of the MAb 6-11A epitope will enable insight into potential mechanisms of immunomodulation and broaden our understanding of the tertiary structure of P1.

Animals↗

PubMed1999

Productivity and some properties of immunoglobulin specific against Streptococcus mutans serotype c in chicken egg yolk (IgY).

Hens were immunized on thighs by using whole cells of Streptococcus mutans MT8148 serotype c strain as antigen through intramuscular (im) and subcutaneous (sc) routes to investigate the difference of immunization reactions and the changes in yolk antibody activities against antigen after initial immunization. Several properties of crude IgY were examined to evaluate the stability during food processing. Results showed that the specificity of IgY of im treated hens was nearly 10 times as high as those of sc treated antibody. IgY from the hens immunized with the serotype c strain showed significant cross-reactions against serotypes e and f, while minor reactions against serotypes a, b, d, and g were observed. In thermal stability tests, IgY activity in both yolk and crude IgY decreased with the increasing temperature, from 70 to 80 degrees C, but the thermal denaturation rates between those two samples were not significantly different. The addition of high levels sucrose, maltose, glycerol, or 2% glycine displayed effective protection against thermal denaturation of IgY. Lyophilized yolk-5% gum arabic powder showed better stability against proteases.

Animals↗

PubMed2006

Glucan-binding proteins are essential for shaping Streptococcus mutans biofilm architecture.

Glucan plays a central role in sucrose-dependent biofilm formation by the dental pathogen Streptococcus mutans. This organism synthesizes several proteins capable of binding glucan. These are divided into the glucosyltransferases that catalyze the synthesis of glucan and the nonglucosyltransferase glucan-binding proteins (Gbps). The biological significance of the Gbps has not been thoroughly defined, but studies suggest that these proteins influence virulence and play a role in maintaining biofilm architecture by linking bacteria and extracellular molecules of glucan. We engineered a panel of Gbp mutants, targeting GbpA, GbpC, and GbpD, in which each gene encoding a Gbp was deleted individually and in combination. These strains were then analyzed by confocal microscopy and the biofilm properties were quantified by the biofilm quantification software comstat. All biofilms produced by mutant strains lost significant depth, but the basis for the reduction in height depended on which particular Gbp was missing. The loss of the cell-bound GbpC appeared dominant as might be expected based on losing the principal receptor for glucan. The loss of an extracellular Gbp, either GbpA or GbpD, also profoundly changed the biofilm architecture, each in a unique manner.

Bacterial Proteins↗

PubMed2002

Inactivation of the Streptococcus mutans fxpC gene confers resistance to xylitol, a caries-preventive natural carbohydrate sweetener.

Xylitol is transported by Streptococcus mutans via a constitutive phosphoenolpyruvate:fructose phosphotransferase system (PTS) composed of a IIABC protein. Spontaneous xylitol-resistant strains are depleted in constitutive fructose-PTS activity, exhibit additional phenotypes, and are associated with the caries-preventive properties of xylitol. Polymerase chain-reactions and chromosome walking were used to clone the fxp operon that codes for the constitutive fructose/xylitol-PTS. The operon contained three open reading frames: fxpA, which coded for a putative regulatory protein of the deoxyribose repressor (DeoR) family, fxpB, which coded for a 1-phosphofructokinase, and fxpC, which coded for a IIABC protein of the fructose-PTS family. Northern blot analysis revealed that these genes were co-transcribed into a 4.4-kb mRNA even in the absence of fructose. Inactivation of the fxpC gene conferred resistance to xylitol, confirming its function. The fxp operon is also present in the genomes of other xylitol-sensitive streptococci, which could explain their sensitivity to xylitol.

Amino Acid Sequence↗

PubMed1989

Dual mechanism for stimulation of glutamate transport by potassium ions in Streptococcus mutans.

An ATP-driven primary transport system operative for L-glutamate or L-aspartate in Streptococcus mutans is, through the entire pH range from 5.5 to 8.5, specifically stimulated by extracellular potassium ions. The stimulation by potassium ions observed in the low pH range between 5.5 and 7 has been interpreted to be due to potassium ion-dependent regulation of the intracellular pH (the first mechanism). In the high pH range from 7 to 8.5, on the other hand, the present study demonstrates that potassium stimulation is essentially not associated with such intracellular pH regulation. This conclusion is based on our observation that potassium stimulation in the high pH range is insensitive to a proton conductor, carbonyl cyanide-p-trifluoromethoxy-phenyl-hydrazone. Since none of the other monovalent cations, including sodium, rubidium, ammonium, and Tris ions, could replace potassium ions in significantly stimulating glutamate transport, it is most likely that the influx of potassium ions specifically cancels the membrane potential derived by movement of glutamate with the net negative charges across a membrane and thus facilitates transport (the second mechanism). The second mechanism appears to be operative even in a low pH range, in addition to the first mechanism.

Adenosine Triphosphate↗

PubMed1982

Sucrose transport by Streptococcus mutans. Evidence for multiple transport systems.

The transport of sucrose by selected mutant and wild-type cells of Streptococcus mutans was studied using washed cocci harvested at appropriate phases of growth, incubated in the presence of fluoride and appropriately labelled substrates. The rapid sucrose uptake observed cannot be ascribed to possible extracellular formation of hexoses from sucrose and their subsequent transport, formation of intracellular glycogen-like polysaccharide, or binding of sucrose or extracellular glucans to the cocci. Rather, there are at least three discrete transport systems for sucrose, two of which are phosphoenolpyruvate-dependent phosphotransferases with relatively low apparent Km values and the other a non-phosphotransferase (non-PTS) third transport system (termed TTS) with a relatively high apparent Km. For strain 6715-13 mutant 33, the Km values are 6.25 X 10(-5) M, 2.4 X 10(-4) M, and 3.0 X 10(-3) M, respectively: strain NCTC-10449, the Km values are 7.1 X 10(-5) M, 2.5 X 10(-4) M and 3.3 X 10(-3) M, respectively. The two lower Km systems could not be demonstrated in mid-log phase glucose-adapted cocci, a condition known to repress sucrose-specific phosphotransferase activity, but under these conditions the highest Km system persists. Also, a mutant devoid of sucrose-specific phosphotransferase activity fails to evidence the two high affinity (low apparent Km) systems, but still has the lowest affinity (highest Km) system. There was essentially no uptake at 4 degrees C indicating these processes are energy dependent. The third transport system, whose nature is unknown, appears to function under conditions of sucrose abundance and rapid growth which are known to repress phosphoenolpyruvate-dependent sucrose-specific phosphotransferase activity in S. mutans. These multiple transport systems seem well-adapted to S. mutans which is faced with fluctuating supplies of sucrose in its natural habitat on the surfaces of teeth.

Biological Transport↗

PubMed2006

[Homology analysis of the extended-V region of the surface proteins in different serotype Streptococcus mutans].

OBJECTIVE: To analysis the homology among the extended-V region of the surface proteins in different serotype Streptococcus mutans (c, f, d, g) and to find out it's significance in anti-caries vaccine. METHODS: The DNA of the bacteria (standarded serotype c, d, f, g and partial serotype c clinicals) was extracted and the extended-V region (SrV+, 1 384-2 514 bp) was amplified using polymerase chain reaction (PCR). Then the products were assessed using restriction fragment length polymorphism (RFLP) by endonuclease Dde I. The genotypings were sequenced and analysised using the program of BLAST on NCBI Gene Bank database. RESULTS: About 1.13 kb fragments were produced both in serotype c and f, the serotype d and g were failed. The RFLP results showed that five different patterns(A, B, C, D, E) among the 117 PCR products were reveled by Dde I. The ration of the genotypings A and B were the most among the strains, the C was lower, the D and E respectively was 1 and 3 strains per genotype. OMZ175 (serotype f) was belong to B genotype. Selected one of the A, B, C genotypings to sequenced and blasted. Then the results of the blastn showed that the identities of the gene sequence were 92%-98% between the serotype c and serotype f, part sequence of the serotype g was homology with the SrV+ of the serotype c, the protein sequence among serotype c, d, f, g were 77%-82%. CONCLUSION: It is reasonable to use some putative pipetides to study the anti-caries vaccine among the extended-V regions of the surface proteins in different serotype (c, d, f, g) in S. mutans.

DNA, Bacterial↗

PubMed1984

Effect of peroral immunization of humans with Streptococcus mutans on induction of salivary and serum antibodies and inhibition of experimental infection.

Naturally occurring antibodies reactive with Streptococcus mutans whole cells were assayed in whole saliva, parotid saliva, and blood samples collected from eight human volunteers. The levels and serotypes of indigenous S. mutans in plaque and whole saliva samples were also determined. After baseline sampling the teeth were cleaned and the subjects were inoculated with streptomycin-resistant S. mutans strains Ingbritt (serotype c) and OMZ65 (serotype g). The level of implantation and duration of colonization were determined in plaque and saliva, and antibodies reactive with these strains were monitored in saliva and serum. After the implanted bacteria were shed, the subjects wee immunized by the daily ingestion of an enteric-coated capsule containing 25 mg of Formalin-killed, freeze-dried OMZ65 cells for 3 days and inoculation was repeated. The levels of antibodies and of implantation and the duration of colonization were monitored as before. One month after the bacteria could no longer be detected, the immunization and inoculation cycle was repeated except that the subjects were immunized for 7 days. Five of the eight subjects were successfully colonized by strains Ingbritt and OMZ65. The remaining three did not become colonized with either strain. Strain OMZ65 implanted at a higher level than did strain Ingbritt. Oral immunization did not result in a detectable antibody response in saliva or serum to whole bacterial cells. However, after both the first and second immunizations there were marked reductions in the peak levels of infection and the duration of colonization of both OMZ65 and Ingbritt.

Adult↗

PubMed1987

Semi-purification of an immunosuppressor substance secreted by Streptococcus mutans that plays a role in the protection of the bacteria in the host.

Crude extracellular products of Streptococcus mutans (CEP-Sm) suppress the proliferative response to phytohaemagglutinin of human peripheral blood mononuclear cells and the primary immune response of C57BL/6 mice to sheep erythrocytes. This immunosuppressive effect favours the survival of the microorganism, and the bacteria lose the ability to secrete immunosuppressor substance if previously subcultured several times. Cells incubated with CEP-Sm and subsequently washed recover the ability to proliferate. Traces of CEP-Sm or to short a time of contact between CEP-Sm and the target immune system induced higher proliferative ratios or higher in vivo immune responses than controls, respectively. The proliferative values of cultures supplemented with CEP-Sm were parallel to the control values up to a certain time, after which they dropped abruptly. This drop is followed by a proliferation, and the higher the amount of CEP-Sm added to the cultures, the shorter the time until the proliferation. CEP-Sm was fractionated by means of ion exchange chromatography followed by double preparative isoelectrofocusing, ending in a subfraction of isoelectric point between 3.9 and 4.2, containing a heat-unstable material stainable by Coomassie blue but unstainable by periodic acid Schiff or methylene blue, and having a maximum optical density of 280 nm.

Animals↗

PubMed2005

Estimation of salivary bacteria capable of inhibiting and stimulating Streptococcus mutans and its correlation to dental caries and untreated carious teeth.

Bacteriocins are bacteriocidal proteinaceous molecules produced by the Gram-positive bacteria not active against the produced strain. Many investigations have revealed that certain bacteria using antibacterial or the inhibitory substance inhibit some other bacteria. A study was conducted in a group of 60 children to ascertain whether any correlation exists between the proportion of salivary bacteria inhibiting and stimulating Streptococcus mutans and the oral health indices (DMFT, deft and Community Periodontal Index of Treatment Needs). A definite inverse correlation was observed between the percentage of salivary inhibiting S. mutans and untreated carious teeth (UCT).

Adolescent↗

PubMed2003

The sloABCR operon of Streptococcus mutans encodes an Mn and Fe transport system required for endocarditis virulence and its Mn-dependent repressor.

Streptococcus mutans belongs to the viridans group of oral streptococci, which is the leading cause of endocarditis in humans. The LraI family of lipoproteins in viridans group streptococci and other bacteria have been shown to function as virulence factors, adhesins, or ABC-type metal transporters. We previously reported the identification of the S. mutans LraI operon, sloABCR, which encodes components of a putative metal uptake system composed of SloA, an ATP-binding protein, SloB, an integral membrane protein, and SloC, a solute-binding lipoprotein, as well as a metal-dependent regulator, SloR. We report here the functional analysis of this operon. By Western blotting, addition of Mn to the growth medium repressed SloC expression in a wild-type strain but not in a sloR mutant. Other metals tested had little effect. Cells were also tested for aerobic growth in media stripped of metals then reconstituted with Mg and either Mn or Fe. Fe at 10 micro M supported growth of the wild-type strain but not of a sloA or sloC mutant. Mn at 0.1 micro M supported growth of the wild-type strain and sloR mutant but not of sloA or sloC mutants. The combined results suggest that the SloABC proteins transport both metals, although the SloR protein represses this system only in response to Mn. These conclusions are supported by (55)Fe uptake studies with Mn as a competitor. Finally, a sloA mutant demonstrated loss of virulence in a rat model of endocarditis, suggesting that metal transport is required for endocarditis pathogenesis.

ATP-Binding Cassette Transporters↗

PubMed2005

Colony forming unit levels of salivary Lactobacilli and Streptococcus mutans in orthodontic patients.

The purpose of this study was to compare the levels of Lactobacilli (LB) and Streptococcus mutans (SM) colony forming units (CFU) in the saliva of subjects before and after orthodontic appliance placement. This was a controlled, prospective two-group, two-measurement, clinical trial performed on 64 study patients, 12-15 years old. Subjects in the experimental group were sampled for LB and SM in stimulated saliva collected on the same day but prior to band and bracket placement. The subjects in the control group were sampled on their first screening appointment two months prior to band and bracket placement. The second samples of LB and SM were taken from the experimental and control groups after two months. Saliva was transferred to a selective agar carrier and incubated for 48 hours at 37 degrees C / 99 degrees F. LB and SM colonies forming units were compared with standard densities. The experimental group wearing orthodontic appliances had significantly higher mean LB CFU counts than the control group at the 2 month follow-up (3.25 vs. 2.57, p = 0.0036). The two groups, however, did not show any difference in mean SM CFU counts at the 2 month follow-up (3.0 vs. 3.1, p = 0.66). The results of this study showed that a higher number of CFUs of LB were associated with the group wearing orthodontic appliances after two months and may play a role in the increased levels of plaque seen in many orthodontic patients.

Adolescent↗