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PubMed1989

Purification and characterization of cell-associated glucosyltransferase synthesizing insoluble glucan from Streptococcus mutans serotype c.

Streptococcus mutans Ingbritt (serotype c) was shown to have a significant amount of cell-associated glucosyltransferase activity which synthesizes water-insoluble glucan from sucrose. The enzyme was extracted from the washed cells with SDS, renatured with Triton X-100, adsorbed to 1,3-alpha-D-glucan gel, and then eluted with SDS. The enzyme preparation was electrophoretically homogeneous, and the specific activity was 7.3 i.u. (mg protein)-1. The enzyme had an Mr of 158,000 as determined by SDS-PAGE, and was a strongly hydrophilic protein, as judged by its amino acid composition. The enzyme gradually aggregated in the absence of SDS. The enzyme had an optimum pH of 6.5 and a Km value of 16.3 mm for sucrose. Activity was stimulated 1.7-fold by dextran T10, but was not stimulated by high concentrations of ammonium sulphate. Below a sodium phosphate buffer concentration of 50 mm, activity was reduced by 75%. This enzyme synthesized an insoluble D-glucan consisting of 76 mol% 1,3-alpha-linked glucose and 24 mol% 1,6-alpha-linked glucose.

Bacterial Proteins↗

PubMed1977

Synthesis of bacteriocins in liquid cultures of Streptococcus mutans.

Strains of Streptococcus mutans synthesized bacteriocins in agar plates, but synthesis of detectable bacteriocins in liquid media took place only under certain culture conditions. The composition of the medium proved to be crucial. Trypticase Soy Broth with 4% Yeast Extract meeting the requirements. The effect of the Yeast Extract is obscure, for some strains also formed detectable bacteriocins in a special Trypticase medium without this agent. It was noted that the broth should be filter-sterilized rather than autoclaved and only a few days old. Attempts at liberating cell-bound bacteriocins from washed cells were unsuccessful, even when they were treated with ultrasound, EDTA, or various chemicals followed by ultrasound. On the basis of size and sensitivity to heat the bacteriocins could be divided into two groups, while their resistance to ether and chloroform and to trypsin did not follow this pattern. Dependence on plasmids could not be demonstrated by attempts at curing with acridine orange or ethidium bromide; and the involvement of phages was unlikely, since the inhibition was not transmissible and phage-like structures were not observed in the electron microscope.

Bacteriocins↗

PubMed2006

Physiologic effects of forced down-regulation of dnaK and groEL expression in Streptococcus mutans.

Strains of Streptococcus mutans lacking DnaK or GroEL appear not to be isolable. To better distinguish the roles played by these chaperones/chaperonins in the physiology of S. mutans, we created a knockdown strategy to lower the levels of DnaK by over 95% in strain SM12 and the level of GroEL about 80% in strain SM13. Interestingly, GroEL levels were approximately twofold higher in SM12 than in the parent strain, but the levels of DnaK were not altered in the GroEL knockdown strain. Both SM12 and SM13 grew slower than the parent strain, had a strong tendency to aggregate in broth culture, and showed major changes in their proteomes. Compared with the wild-type strain, SM12 and SM13 had impaired biofilm-forming capacities when grown in the presence of glucose. The SM12 strain was impaired in its capacity to grow at 44 degrees C or at pH 5.0 and was more susceptible to H(2)O(2), whereas SM13 behaved like the wild-type strain under these conditions. Phenotypical reversions were noted for both mutants when cells were grown in continuous culture at a low pH, suggesting the occurrence of compensatory mutations. These results demonstrate that DnaK and GroEL differentially affect the expression of key virulence traits, including biofilm formation and acid tolerance, and support that these chaperones have evolved to accommodate unique roles in the context of this organism and its niche.

Bacterial Proteins↗

PubMed2005

LuxS-based signaling affects Streptococcus mutans biofilm formation.

Streptococcus mutans is implicated as a major etiological agent in human dental caries, and one of the important virulence properties of this organism is its ability to form biofilms (dental plaque) on tooth surfaces. We examined the role of autoinducer-2 (AI-2) on S. mutans biofilm formation by constructing a GS-5 luxS-null mutant. Biofilm formation by the luxS mutant in 0.5% sucrose defined medium was found to be markedly attenuated compared to the wild type. Scanning electron microscopy also revealed that biofilms of the luxS mutant formed larger clumps in sucrose medium compared to the parental strain. Therefore, the expression of glucosyltransferase genes was examined and the gtfB and gtfC genes, but not the gtfD gene, in the luxS mutant were upregulated in the mid-log growth phase. Furthermore, we developed a novel two-compartment system to monitor AI-2 production by oral streptococci and periodontopathic bacteria. The biofilm defect of the luxS mutant was complemented by strains of S. gordonii, S. sobrinus, and S. anginosus; however, it was not complemented by S. oralis, S. salivarius, or S. sanguinis. Biofilm formation by the luxS mutant was also complemented by Porphyromonas gingivalis 381 and Actinobacillus actinomycetemcomitans Y4 but not by a P. gingivalis luxS mutant. These results suggest that the regulation of the glucosyltransferase genes required for sucrose-dependent biofilm formation is regulated by AI-2. Furthermore, these results provide further confirmation of previous proposals that quorum sensing via AI-2 may play a significant role in oral biofilm formation.

Bacterial Proteins↗

PubMed2001

[Construction of eukaryotic expression plasmid pcDNA3-gtfB expressing glucosyltransferase B of Streptococcus mutans].

OBJECTIVE: Glucosyltransferase (GTF) of Streptococcus mutans is considered as a cariogenic virulence factor due to its ability to synthesize glucan, which facilitate sucrose-depended adherence and cell-to-cell accumulation of bacteria. In this study, gtfB, the target gene fragment which encodes multiple catalytic sites and antigen epitopes of GTF, was recombined into eukaryotic expression vector pcDNA3. The feasibility of the recombination plasmid pcDNA3-gtfB used as gene vaccine will be investigated in further study. METHODS: The target gene fragment gtfB (904-4578 bp) was obtained by standard PCR amplification while genome DNA of streptococcus mutans GS-5 was used as template. Then the PCR products were extracted and purified from low-melting temperature agarose. The gtfB and plasmid pcDNA3 were cut by Kpn I, Xho I, and the digested products were extracted and purified again for recombination. The purified gtfB and plasmid pcDNA3 were recombined by T4 DNA ligase, ligation products were transformed into competent cell, Escherichia coli JM109. Transformed colonies were screened by Ampr LB plate, then recombined plasmids were isolated and identified by restricted endonuclease cutting and Sanger dideoxy DNA sequencing. RESULTS: Identified by agarose gel electrophoresis, the target gene-gtfB obtained PCR amplification had the same molecular size (36 kb) as predicted. It was indicated that recombined plasmids contained inserted gtfB gene fragment by restricted endonuclease cut analysis, the sequencing data also indicated that inserted gtfB gene had correct DNA sequence and orientation according to DNA sequence of Streptococcus mutans GS-5 (gene bank M17361). CONCLUSION: Inserted gene-gtfB of recombined plasmid pcDNA3-gtfB encoded multiple catalytic sites and epitopes. It was proved that these epitopes had high immune antigenicity and that antiserum could significantly inhibit the synthesis of water-insoluble glucans and water-soluble glucan. In vitro adherence experiment also indicated that it could inhibit streptococcus mutans adherence to saliva-coated hydroxyapatite. Vector pcDNA3 was high expressing eukaryotic vector, and could stimulate antigen-representing cell. It was suggested that recombined plasmid pcDNA3-gtfB had high immune antigenicity and immune responsiveness, and this supported its use as gene vaccine candidates in the development of anti-caries vaccines.

Dental Caries↗

PubMedDate not supplied

Correlation among mutans streptococci counts, dental caries, and IgA to Streptococcus mutans in saliva.

Two-hundred and forty individuals were studied, divided into five groups as follows: caries-free children, children with caries, children with rampant caries, young adults with and without caries. Whole stimulated saliva was collected and all individuals were investigated for DMFT/dmft according to the WHO criteria and the simplified oral hygiene index (OHI-S). Quantitative analysis of the total aerobic flora and mutans streptococci in saliva was performed. Also, the level of salivary anti-S. mutans IgA was determined by ELISA. Children with rampant caries showed the highest OHI-S value. The highest total counts of microorganisms were found in the group of children with caries. No statistically significant differences were observed for salivary flow, OHI-S and microorganism counts between the groups of young adults. No correlation between mutans streptococci counts and anti-Streptococcus mutans IgA levels was observed in the studied groups. A correlation between increased anti-Streptococcus mutans IgA levels and caries-free status was observed among young adults but not among children.

Adolescent↗

PubMed1980

Manganese antagonizes the inhibitory effect of fluoride on the glucose metabolism of Streptococcus mutans.

Manganese stimulated the utilization of glucose by Streptococcus mutans, Streptococcus sanguis, Streptococcus mitior and Streptococcus milleri. S. mutans serotype c strains formed larger amounts of intracellular polysaccharide, lactic acid and produced a lower terminal pH in glucose broth when grown in the presence of 0.5 mM Mn. Manganese stimulated the utilization of glucose by resting cell suspensions of each of the four oral streptococcal species examined. Fluoride inhibited the utilization of glucose by the streptococci and Mn, but not calcium or magnesium, was found to counteract the inhibitory effect of fluoride.

Fluorides↗

PubMed1975

Glucose-6-phosphate-dependent pyruvate kinase in Streptococcus mutans.

Pyruvate kinase of Streptococcus mutans JC 2 had an absolute and specific requirement for glucose-6-phosphate. Inorganic phosphate was a strong inhibitor. The enzyme required K+ or NH4+ and Mg2+ or Mn2+. S. mutans FIL and E 49, Streptococcus bovis ATCC 9809, and Streptococcus salivarius ATCC 13419 had also glucose-6-phosphate-dependent pyruvate kinases, whereas Streptococcus sanguis NCTC 10904 had an enzyme activated by fructose-1,6-diphosphate.

Ammonia↗

PubMed1987

Characterization of a rat salivary sialoglycoprotein complex which agglutinates Streptococcus mutans.

Rat saliva agglutinated Streptococcus mutans Ingbritt and NCTC 10449 and Streptococcus sanguis NCTC 7864 but not S. mutans NCTC 10921, GS 5, or LM 7, Streptococcus sobrinus 6715-13 or OMZ 65, or Streptococcus cricetus HS 6, as measured turbidometrically. The specificity of agglutination by rat saliva was the same as that by human saliva. Agglutination was associated with a mucin complex (rat salivary agglutinin complex [rS-A]) of sulfated sialoglycoproteins, with a trace of associated lipid and an apparent Mr of 1.6 X 10(6), isolated by gel-filtration Fast Protein Liquid Chromatography. The complex was dissociated in a high-ionic-strength buffer containing 6 M urea and then fractionated by gel filtration and anion-exchange Fast Protein Liquid Chromatography into four sulfated sialoglycoprotein components, designated rS-A-1Q1, rS-A-1Q2, rS-A-1Q3, and rS-A-2, with rS-A-1Q2 being polydisperse through differential glycosylation of the polypeptide backbone. The dissociation destroyed agglutination activity. The polypeptide backbones contained up to 42% serine plus threonine and up to 40% glycine plus alanine plus proline plus valine. The carbohydrate moiety of the rS-A sialoglycoproteins consisted of N-acetylgalactosamine, sialate, galactose, fucose, N-acetylglucosamine, and small amounts of mannose, with the predominant sugar being N-acetylgalactosamine. Agglutination was inhibited by 1 mM EDTA but was restored by 1.5 mM CaCl2. Agglutination was also inhibited by 5 mM CaCl2; nonimmune sera; cationic polymers; and wheat germ, lentil, soybean, and peanut lectins. However, agglutination was not affected by lipoteichoic acid, various anionic proteins, or various sugars. Neuraminidase treatment of rS-A did not affect activity, but tryptic digestion of S. mutans did prevent agglutination. The results are consistent with calcium bridging the negative groups within the rS-A complex and allowing the approach of rS-A to the bacterial cell surface to effect a specific conformational attachment.

Agglutinins↗

PubMed1980

[Degradation of collagen by the cariogenic bacteria, Streptococcus mutans].

The behaviour of cariogenic Bacteria (Streptococcus mutans) is studied with regard to collagen, which represents 90% of the dentine organic matrix. Collagenase activity of cariogenic Bacteria is measured with radioactive precursors and gel electrophoresis and compared to reference bacterial collagenase (Clostridium histolyticum). Labelled collagen substrate has been prepared with two different methods: extraction by 0,5 M acetic acid from young Rat skin, previously labelled with L-proline 14C, or reduction by Na B3H4. Both collagen sutstrates have been incubated for 2 h in Terleckyj medium in which the Streptococcus mutans have been inoculated. The experiments show a proteolytic activity of Streptococcus Mutans on the collagen substrate.

Animals↗

PubMedDate not supplied

Restoration-related salivary Streptococcus mutans level: a dental caries risk factor?

OBJECTIVES: The salivary level of Streptococcus mutans related to filled teeth was compared with the levels related to decayed and sound teeth, in order to establish whether the presence of restorations may increase the risk of infection of other teeth by Streptococcus mutans. METHODS: The sound, decayed and filled teeth were recorded in 809, 6-7-year-old school-children. Salivary Streptococcus mutans detection (i.e. more than 1 x 10(4) CFU/ml) and counts were evaluated. Streptococcus mutans log count means and prevalence values of subjects with only sound teeth (group 1), with filled, without decayed teeth (group 2), with decayed, without filled teeth (group 3), were calculated and compared using the Student's t-test and the chi-square test. The effect of filled, decayed and sound teeth on Streptococcus mutans level was also evaluated using logistic regression. RESULTS: Log count means and prevalence values of group 2 subjects were significantly lower than values of group 3 subjects (means, 0.92 vs 1.66: prevalence, 73.17% vs 94.63%) and statistically not-different from values of group 1 subjects (mean. 0.75: prevalence, 70.06%). The logistic regression analysis showed that the factors significantly increasing the risk of Streptococcus mutans being detected in saliva were only primary and/or permanent decayed teeth. The risk of Streptococcus mutans being detected in saliva was not affected by filled teeth more than sound teeth. CONCLUSIONS: In the present study population, the salivary Streptococcus mutans level attributable to filled teeth was low; this suggests that treatment of a carious lesion would cause a lowering of Streptococcus mutans concentration to the same levels as those shown by healthy subjects, thus reducing the risk of infection to other teeth.

Child↗

PubMed2000

Identification of a new gene responsible for the oxygen tolerance in aerobic life of Streptococcus mutans.

Alkyl hydroperoxide reductase in Streptococcus mutans consists of two components, Nox-1 and AhpC. Deletion of nox-1 and ahpC in a double mutant as well as the wild-type of Streptococcus mutans can form colonies in the presence of air to the same extent. The evidence suggested the presence of some other antioxidant system(s) independent of the Nox-1/AhpC system in the bacterium. Here we identified a new antioxidant gene (dpr) and the gene product (Dpr) which complements the defect of peroxidase activity caused by the deletion of nox-1 and ahpC in S. mutans. The dpr-disruption mutant of S. mutans could form colonies anaerobically but not aerobically.

Aerobiosis↗

PubMed1996

Characterization of a P1-deficient strain of Streptococcus mutans that expresses the SpaA protein of Streptococcus sobrinus.

The Streptococcus sobrinus SpaA protein and the Streptococcus mutans P1 protein share 66% sequence homology at the amino acid level. To determine if the SpaA protein can be expressed in S. mutans and functionally replace the P1 protein, the spaA gene of S. sobrinus 6715 was isolated from plasmid pX1303 and inserted into the Escherichia coli-Streptococcus shuttle vector pVA838. The resulting plasmid pX1600 was transformed into the P1-deficient strain S. mutans 834 that has defects in saliva-mediated aggregation and in the ability to adhere to saliva-coated hydroxyapatite surfaces. Western blot (immunoblot) analysis of cellular protein fractions of S. mutans 834 (pX1600) detected in mutanolysin-solubilized cell walls a major protein of 210 kDa with an electrophoretic mobility similar to that of S. sobrinus SpaA protein and a minor 210-kDa protein and a major 64-kDa protein in the extracellular protein fraction. Analysis of virulence traits showed that expression of SpaA protein by S. mutans 834(pX1600) cells had restored the ability of the S. mutans 834 cells to aggregate in the presence of saliva or salivary agglutinin but not to adhere to saliva-coated hydroxyapatite. This cell aggregation was inhibited specifically by antisera to S. sobrinus SpaA protein. These results indicate that SpaA plays a role in the virulence of S. sobrinus by specifically interacting with fluid-phase salivary agglutinin to mediate cell aggregation.

Agglutinins↗

PubMed2005

[The study of salivary-SIgA reaction to Streptococcus mutans in acid environment].

OBJECTIVE: To test the salivary immunoglobulin A antibody activity to Streptococcus mutans in normal with in acid environment. METHODS: Streptococcus mutans strains were isolated from 20 volunteers, serotyped by biochemical test and PCR, and genotyped by AP-PCR. Unstimulated secretions from submandibular glands and sublingual glands were collected from volunteers by modified collectors. Each identified Streptococcus mutans genotype was cultured in two groups: control group was cultured in BHI broth pH7.2 at 37 degrees C for 2 h; acid shock group were cultured in TYEG broth (pH5.5) at 37 degrees C for 2 h. Analysis of SIgA activity to Streptococcus mutans genotypes in different groups was detected by Western blot. RESULTS: (1) The SIgA of each individual could response to his own Streptococcus mutans strains and the reference strains; (2) The same individual had different SIgA activity to different genotype strains; (3) There were no significant difference between acid groups and control groups, in spite that some bands had strong or weak intensity. CONCLUSIONS: Although Streptococcus mutans could express acid shock proteins in stress, the present study suggests that these new proteins have no qualitative effect on the reaction of SIgA to Streptococcus mutans.

Adult↗

PubMed1988

Molecular basis for the spontaneous generation of colonization-defective mutants of Streptococcus mutans.

Spontaneous mutants of Streptococcus mutans GS-5 defective in sucrose-dependent colonization of smooth surfaces are generated at frequencies above the spontaneous mutation rate. Southern blot analysis of such mutants suggested rearrangement of the genes coding for glucosyltransferase (GTF) activity. Two strain GS-5 homologous tandem genes, gtfB and gtfC, coding for GTF-I and GTF-S activities respectively, were demonstrated to undergo recombination when introduced into recombination-proficient Escherichia coli transformants. However, the two genes were quite stable when transformed on a single DNA fragment into a recA mutant of E. coli. The DNA fragment coding for GTF activity from one S. mutans colonization-defective mutant, SP2, was isolated and shown also to have undergone recombination between the gtfB and gtfC genes, resulting in reduced GTF activity. These results are discussed relative to the in vivo generation of colonization-defective mutants in cultures of S. mutans.

Cloning, Molecular↗

PubMed1977

Bacteriophage deoxyribonucleic acid-induced mutation of Streptococcus mutans.

A cariogenic strain, Streptococcus mutans PK 1, has been demonstrated to have prophage by observation of phage particles with an electron microscope and by induction with mitomycin C. The phage particles could not be detected in a mutant strain which lost the characteristic adhesive nature on glass surfaces and exhibited diminished ability to synthesize insoluble polysaccharide. By infecting the mutant cells with the phages or with free phage deoxyribonucleic acid isolated from the parent strain of S. mutans PK1, the mutant cells were transformed to the cariogenic strain with adhesive nature. The transformants retained the general characteristics of S. mutans PK 1, but in addition all transformants showed a new character; namely, the transformant cell could produce ammonia from arginine, whereas neither the parent nor mutant strains of S. mutans PK 1 had such a property;

Ammonia↗

PubMed1981

Insoluble glucan synthesis by mutansucrase as a determinant of the cariogenicity of Streptococcus mutans.

Five strains of Streptococcus mutans were grown in continuous culture with either a limited supply or an excess of glucose. Proteins secreted into the extracellular fluid by strains C67-1, 3209 and K1 rapidly catalysed the synthesis of insoluble glucan from sucrose (mutansucrase activity). The culture fluid from strains Ingbritt or C67-25 catalysed the synthesis of soluble glucan (dextransucrase activity) and fructan, but little or no mutansucrase activity was detected. The strains which secreted active mutansucrase readily colonized a smooth hard surface during growth in batch culture and were more cariogenic in pathogen-free rats than those which secreted little mutansucrase activity. There was no similar correlation between fructosyltransferase, dextransucrase or total glucosyltransferase activity and either adherence or cariogenicity. We conclude that the ability to catalyse insoluble glucan synthesis is a major determinant of the cariogenicity of S. mutans strains.

Animals↗

PubMed1982

Serotype specificity for some biochemical characteristics of Streptococcus mutans.

Representative strains of Streptococcus mutans serotypes a to g were examined for characteristic in vitro traits thought to contribute to cariogenic virulence. Most strains of serotypes a, d and g produced higher proportion of the cell-associated, alkali-soluble glucans from sucrose. Cells of these serotypes agglutinated upon addition of high-molecular-weight dextrans or sucrose, but did not adsorb well to saliva-coated hydroxyapatite. Serotype c, e and f strains, by contrast, synthesized higher proportions of the extracellular, water-soluble glucans and adsorbed well to saliva-coated hydroxyapatite particles but did not agglutinate with dextrans. Thus, serotype a, d and g S. mutans and type c, e and f S. mutans formed two separate groups on the basis of these biochemical properties. Synthesis of intracellular iodophilic polysaccharides from glucose showed a different pattern of distribution among the serotypes: types a, d, e and f synthesized large amounts of this polysaccharide, while all but one of the eight type c and g strains produced only small amounts. Serotype b S. mutans seemed to constitute a separate subgroup in terms of the above in vitro traits.

Agglutination↗