| inhibition of porphyromonas gingivalis adhesion to streptococcus gordonii by human submandibular-sublingual saliva. | porphyromonas gingivalis w50 adheres in vitro to biofilms of streptococcus gordonii g9b. this phenomenon is believed to facilitate the initial colonization of the oral cavity by p. gingivalis and to contribute to the maturation of dental plaque. in this report, we describe the modulating effects of human submandibular-sublingual saliva (hsmsl) on this in vitro model of intergeneric bacterial adhesion (coaggregation). hsmsl inhibited p. gingivalis adhesion to s. gordonii by 50% at a concentration ... | 1992 | 1319402 |
| de novo glucan synthesis by mutants streptococcal glucosyltransferases present in pellicle promotes firm binding of streptococcus gordonii to tooth surfaces. | adherence of 3h-labelled cells of streptococcus gordonii and streptococcus milleri to artificial pellicles prepared from saliva supplemented with glucosyltransferases from mutants streptococci was examined using a new assay for sucrose-dependent cell-to-pellicle attachment. results indicate that s. gordonii, but not s. milleri, could attach tightly to hydroxylapatite surfaces through de novo glucan synthesis by mutants streptococcal glucosyltransferases present in the experimental salivary pelli ... | 1992 | 1327954 |
| adherence, coaggregation, and hydrophobicity of streptococcus gordonii associated with expression of cell surface lipoproteins. | streptococcus gordonii challis incorporated exogenous [3h]palmitate into 13 polypeptides extractable from intact cells with sodium dodecyl sulfate. a 76-kda surface-exposed polypeptide, implicated previously as a cell aggregation determinant, was shown to be one of these lipid-modified polypeptides. differences in sodium dodecyl sulfate-polyacrylamide gel electrophoresis patterns of lipopolypeptides were detected with mutants of s. gordonii that were altered in adherence, aggregation, coaggregat ... | 1992 | 1339408 |
| restriction endonuclease-fragment polymorphisms of oral viridans streptococci, compared by conventional and field-inversion gel electrophoresis. | oral streptococci formerly classified as streptococcus sanguis or streptococcus mitis have recently been divided into four species. two additional species have also been proposed for this group. each species is genetically distinct, but they have many traits in common, which makes it difficult for clinical isolates to be identified by phenotypic tests. genotypic comparison may provide an alternative approach. this study used dna fingerprint analysis for comparison of genotypes of 21 reference st ... | 1992 | 1351484 |
| use of a replica-plate assay for the rapid assessment of salivary protein-bacteria interactions. | a replica-plate assay was used to screen for the interaction of salivary molecules with dental plaque bacteria. bacterial colonies cultured from supragingival plaque on sheep-blood (sb) agar were replica-plated onto nitrocellulose membranes overlaying sb or mitis-salivarius agar. membranes with attached colonies were removed and incubated with 125i-amylase or 125i-proline-rich glycoprotein (prg). positive interactions were detected by autoradiography. only strains of streptococcus gordonii and a ... | 1992 | 1382259 |
| characterization of an amylase-binding component of streptococcus gordonii g9b. | the goal of the present study was to begin characterizing the amylase-binding component(s) on the surface of streptococcus gordonii g9b. alkali extracts but not phenol-water extracts of this bacterium inhibited 125i-amylase binding to s. gordonii g9b. to identify the bacterial components involved in amylase binding, the alkali extract was subjected to affinity chromatography on amylase-sepharose. immunoblotting with a rabbit antiserum against s. gordonii g9b revealed that a 20-kda streptococcal ... | 1992 | 1383157 |
| glucosyltransferase phase variation in streptococcus gordonii modifies adhesion to saliva-coated hydroxyapatite surfaces in a sucrose-independent manner. | phase variation of streptococcus gordonii between high (spp+) and low (spp-) levels of glucosyltransferase (gtf) activity resulted in the greater adhesion of spp- strains to saliva-coated hydroxyapatite (s-ha) in a washed-cell adhesion test. specific gtf mutants did not show this response. although washed spp+ cells produced 5-fold or more glucan from sucrose than spp- cells did under the conditions of the adhesion test, sucrose elevated the adhesion of both phenotypes to hydroxyapatite (ha) equ ... | 1992 | 1388259 |
| adhesion of glucosyltransferase phase variants to streptococcus gordonii bacterium-glucan substrata may involve lipoteichoic acid. | growing streptococcus gordonii spp+ phase variants, which have normal levels of glucosyltransferase (gtf) activity, use sucrose to promote their accumulation on surfaces by forming a cohesive bacterium-insoluble glucan polymer mass (bpm). spp- phase variants, which have lower levels of gtf activity, do not form bpms and do not remain in bpms formed by spp+ cells when grown in mixed cultures. to test the hypothesis that segregation of attached spp+ and unattached spp- cells was due to differences ... | 1992 | 1398940 |
| purification and properties of sorbitol-6-phosphate dehydrogenase from oral streptococci. | the activity of sorbitol-6-phosphate (s6p) dehydrogenase (s6pdh) and the sorbitol transport system were studied in strains of the oral streptococci streptococcus gordonii, streptococcus mitis, streptococcus sanguis and streptococcus mutans. genetically transformed (to ferment sorbitol) strains and their dna donors were included. s6pdh was purified by anion exchange chromatography and gel filtration. the purity of the enzyme was confirmed by polyacrylamide gel electrophoresis. the purified enzyme ... | 1992 | 1408350 |
| expression of m6 protein gene of streptococcus pyogenes in streptococcus gordonii after chromosomal integration and transcriptional fusion. | the m6 protein of streptococcus pyogenes was expressed on the cell surface and secreted in streptococcus gordonii challis (formerly streptococcus sanguis) after chromosomal integration of a promoterless m6 protein gene (emm-6.1). the ermc gene, conferring resistance to erythromycin, was cloned downstream of emm-6.1, within the same clai fragment. the initiation codon of emm-6.1 was 19 bp downstream of a clai site, so that clai cleavage would leave the gene promoterless. the clai fragment contain ... | 1992 | 1448621 |
| gene disruption identifies a 290 kda cell-surface polypeptide conferring hydrophobicity and coaggregation properties in streptococcus gordonii. | the c-terminal coding region of the gene (denoted csha) encoding a high-molecular-mass (290 kda) cell-surface polypeptide in the oral bacterium streptococcus gordonii was cloned and sequenced. insertion of ermam into the s. gordonii chromosome at the 3' end of the coding region of csha led to the production of isogenic mutants that secreted a truncated form (260 kda) of the csha polypeptide into the growth medium. mutants had reduced cell-surface hydrophobicity and were impaired in their ability ... | 1992 | 1479886 |
| influence of saliva on aggregation and adherence of streptococcus gordonii hg 222. | the influence of saliva on the aggregation and adherence of streptococcus gordonii hg 222 was studied. the aggregation was measured spectrophotometrically, and the adherence of s. gordonii to microtiter plate wells was measured in an enzyme-linked immunosorbent assay system. the aggregation of hg 222 was induced primarily by mucous saliva, whereas the adherence of hg 222 to microtiter plates was mediated by both mucous and serous saliva. fractions of submandibular saliva, obtained by gel filtrat ... | 1992 | 1500195 |
| characterization of two plasmids from campylobacter jejuni isolates that carry the apha-7 kanamycin resistance determinant. | two small plasmids of 11.5 and 9.5 kb, each carrying an apha-7 kanamycin phosphotransferase gene, were studied. the mics of kanamycin for the two human campylobacter jejuni isolates harboring the plasmids were 10,000 and 5,000 micrograms/ml, while the mics of amikacin were 32 and 8 micrograms/ml, respectively. the mics of gentamicin and tobramycin were less than or equal to 2 micrograms/ml for both isolates. the restriction endonuclease maps of the plasmids were similar, with the larger plasmid ... | 1992 | 1503433 |
| induction of a putative laminin-binding protein of streptococcus gordonii in human infective endocarditis. | there is evidence to suggest that the virulence of streptococcus strains in infective endocarditis might be due to the expression of binding sites for the extracellular matrix proteins of damaged valves. in this communication, we draw attention to one laminin-binding protein from a strain of streptococcus gordonii isolated from a patient with human endocarditis. this 145-kda protein was found on the cell wall of the bacterium. the level of expression of this binding protein might be regulated by ... | 1992 | 1530927 |
| identification of a gene, rgg, which regulates expression of glucosyltransferase and influences the spp phenotype of streptococcus gordonii challis. | streptococcus gordonii challis was previously shown to give rise to phase variants expressing high (spp+) or low (spp-) levels of extracellular glucosyltransferase (gtf) activity. here, shotgun cloning of an s. gordonii spp+ chromosomal digest resulted in a chimeric plasmid (pam5010) able to complement the spp- phenotype. in addition, introduction of pam5010 into an spp+ strain resulted in a 10-fold increase in gtf expression. deletion analysis of pam5010 identified a 1.2-kb dna segment which ex ... | 1992 | 1534326 |
| delivery and expression of a heterologous antigen on the surface of streptococci. | we have developed a system in which a foreign antigen replaces nearly all of the surface-exposed region of the fibrillar m protein from streptococcus pyogenes and is fused to the c-terminal attachment motif of the m molecule. the fusion protein is thus expressed on the surface of streptococcus gordonii, a commensal organism of the oral cavity. the antigen chosen to be expressed within the context of the m6 molecule was the e7 protein (98 amino acids) of human papillomavirus type 16. stable recom ... | 1992 | 1563781 |
| nucleotide sequence of a gene coding for a saliva-binding protein (ssab) from streptococcus sanguis 12 and possible role of the protein in coaggregation with actinomyces. | the nucleotide sequence of a 2.9-kb streptococcal dna fragment which codes for two proteins with mrs of 36,000 (streptococcus sanguis adhesin b [ssab]) and 20,000 has been determined. the ssab gene is 927 bp and codes for a 34,684-da protein. the open reading frame coding for the 20-kda protein is 489 bp and codes for a protein of 17,885 da. the ssab protein has a putative hydrophobic 19-amino-acid signal sequence resulting in a 32,620-mr secreted protein, whereas the 20-kda protein has no signa ... | 1991 | 1671775 |
| sucrose-promoted accumulation of growing glucosyltransferase variants of streptococcus gordonii on hydroxyapatite surfaces. | streptococcus gordonii exhibits a phase variation involving expression of high (spp+) or low (spp-) glucosyltransferase activity. the related bacterial accumulation on hydroxyapatite (ha) and saliva-coated ha surfaces was examined and found to be significant. spp+ cells growing anaerobically in a defined medium utilize about 30% of the glucose available from sucrose to make insoluble glucans. these glucans formed cohesive masses on ha beads, which contained 80 to 90% of the total bacteria. the b ... | 1991 | 1716611 |
| adherence of oral streptococci to salivary glycoproteins. | we used an overlay method to study the ability of human salivary glycoproteins to serve as receptors for several strains of streptococci that colonize the oral cavity. parotid and submandibular-sublingual salivas were collected as ductal secretions, separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and transferred to nitrocellulose membranes. the resulting blots were overlaid with [35s]methionine-labeled bacteria, and salivary components to which the bacteria bound were det ... | 1992 | 1729194 |
| ecological implications of glucosyltransferase phase variation in streptococcus gordonii. | when sucrose is provided as a substrate for glucosyltransferase (gtf), spp+ cells of the oral bacteria streptococcus gordonii grow embedded in an insoluble glucan mass associated with surfaces. spp- phase variants with lower gtf activity, which either arise from or are grown with spp+ cells, segregate preferentially as unattached cells in the culture supernatants. conversely, spp+ revertants preferentially accumulate on surfaces. gtf phase variation, therefore, may facilitate the dispersion of s ... | 1991 | 1838470 |
| mutants of streptococcus gordonii challis over-producing glucosyltransferase. | two mutants of streptococcus gordonii which over-produced extracellular polysaccharide when grown on sucrose-containing medium were isolated after mutagenesis of strain challis with ethyl methanesulphonate. the mutants, designated strains ob20 and ob30, expressed 2.6-fold and 4.7-fold respectively more glucosyltransferase (gtf) activities than the wild-type strain. transformation experiments suggested that the two mutants carried different mutations, denoted gtf-20 and gtf-30. a double mutant (g ... | 1991 | 1851801 |
| delineation of a segment of adsorbed salivary acidic proline-rich proteins which promotes adhesion of streptococcus gordonii to apatitic surfaces. | cells of several strains of streptococcus gordonii attached in much higher numbers to experimental pellicles formed from samples of submandibular or parotid saliva on hydroxyapatite (ha) beads than to buffer controls. the nature of the salivary components responsible were investigated by preparing experimental pellicles from chromatographic fractions of submandibular saliva obtained from trisacryl gf 2000m columns. adhesion of s. gordonii blackburn was promoted by two groups of fractions. the ad ... | 1991 | 1879920 |
| subclass distribution of salivary secretory immunoglobulin a antibodies to oral streptococci. | the ability of specific secretory immunoglobulin a (s-iga) antibodies to inhibit bacterial colonization of mucosal surfaces may be neutralized by the activity of bacterial iga1 proteases. because of the resistance of the iga2 subclass to these enzymes, the biological effect of iga1 proteases in vivo may depend on the subclass distribution of the bacterium-specific antibodies. we have estimated the subclass distribution of s-iga antibodies in saliva samples from 13 individuals against iga1 protea ... | 1991 | 1894364 |
| ecology of viridans streptococci in the oral cavity and pharynx. | recently published taxonomic studies of viridans streptococci have resulted in several changes in the nomenclature and definition of oral streptococcal species. with this background, the ecology of streptococci in the oropharyngeal cavities was reinvestigated. the results based on the examination of 1426 streptococcal isolates confirmed and extended earlier findings. apart from mature supragingival plaque, which contained a mixture of all orally encountered streptococci, each site showed a chara ... | 1991 | 1945494 |
| detection of immunoglobulin a1 protease-induced fab alpha fragments on dental plaque bacteria. | the mechanisms by which immunoglobulin a1 (iga1) protease activity may enable bacteria to evade the effect of specific secretory iga (s-iga) antibodies are not clear. a possibility which has received indirect experimental support is that bacteria, as a consequence of the protease activity, become coated with incompetent fab alpha fragments instead of with intact antibody molecules. using a combination of nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting, we ... | 1991 | 1987074 |
| structural relationship between the enzymatic and streptococcal binding sites of human salivary alpha-amylase. | previous studies have demonstrated that human salivary alpha-amylase specifically binds to the oral bacterium streptococcus gordonii. this interaction is inhibited by substrates such as starch and maltotriose suggesting that bacterial binding may involve the enzymatic site of amylase. experiments were performed to determine if amylase bound to the bacterial surface possessed enzymatic activity. it was found that over one-half of the bound amylase was enzymatically active. in addition, bacterial- ... | 1990 | 2125215 |
| characterization of the alpha-amylase receptor of streptococcus gordonii nctc 7868. | the purpose of the work described here was to investigate the mechanisms involved in the binding of salivary alpha-amylase to streptococcus gordonii nctc 7868 (challis). of six types of alpha-amylase studied, only mammalian forms of the enzyme were found to bind to s. gordonii cells. salivary alpha-amylase binding was inhibited by treatment of cells with trypsin and pronase, but not with pepsin or sodium periodate. presence of starch, dextrin, or maltoheptaose partially inhibited binding of the ... | 1990 | 2172340 |
| coaggregation of streptococcus sanguis and other streptococci with candida albicans. | thirteen strains of viridans group streptococci and two strains of other streptococci were tested for coaggregation with candida albicans. streptococcus sanguis strains generally exhibited low levels of adherence to 28 degrees c-grown exponential-phase yeast cells, but starvation of yeast cells for glucose at 37 degrees c (or at 28 degrees c) increased their coaggregating activity with these streptococci by at least tenfold. this was a property common to four c. albicans strains tested, two of w ... | 1990 | 2182544 |
| insertional inactivation of the gene encoding a 76-kilodalton cell surface polypeptide in streptococcus gordonii challis has a pleiotropic effect on cell surface composition and properties. | a library of streptococcus gordonii dl1-challis dna was constructed in lambda gt11. phage plaques were screened for production of antigens that reacted with antiserum to s. gordonii cell surface proteins. a recombinant phage denoted lambda gt11-cp2 was isolated that carried 1.85 kb of s. gordonii dna and that expressed an antigen with a molecular mass of 29 kda in escherichia coli. antibodies that reacted with the expression product were affinity purified and were shown to react with a single po ... | 1990 | 2228239 |
| ability to bind salivary alpha-amylase discriminates certain viridans group streptococcal species. | a collection of 144 viridans group streptococcal strains recently characterized as part of a taxonomic study was examined for the ability to bind salivary alpha-amylase. this property was found in most strains of streptococcus gordonii and streptococcus mitis and in occasional strains of streptococcus anginosus and streptococcus salivarius. in contrast, all strains of streptococcus sanguis, streptococcus oralis, streptococcus vestibularis, and streptococcus mutans lacked alpha-amylase-binding ca ... | 1990 | 2254435 |
| comparison of the initial streptococcal microflora on dental enamel in caries-active and in caries-inactive individuals. | this study compared the initial (4 h) microflora on enamel in 7 caries-active and in 7 caries-inactive adolescents. in both groups the microflora was dominated by streptococci which comprised 61 and 78% (median values) of the total viable counts in caries-active and caries-inactive individuals, respectively (p less than 0.01). identification of a total of 700 streptococcal isolates according to a recently revised classification showed that the predominant streptococci belonged to the species str ... | 1990 | 2276164 |
| characterization of streptococcus gordonii (s. sanguis) pk488 adhesin-mediated coaggregation with actinomyces naeslundii pk606. | intergeneric coaggregation of streptococcus gordonii (s. sanguis) pk488 and actinomyces naeslundii pk606 was studied by using coaggregation-defective (cog-) mutants of both strains. a streptococcal protein of 38 kilodaltons was identified with anti-s. gordonii serum absorbed with cog- cells of the streptococcus. absorbed immunoglobulin g specifically blocked coaggregation of the streptococcus-actinomyces pair but did not affect the coaggregation of the streptococcus with other coaggregation part ... | 1990 | 2387635 |
| immunization of mice by oral colonization with live recombinant commensal streptococci. | to test the use of recombinant streptococci as live vaccine vectors, colonization/immunization experiments were performed with streptococcus gordonii expressing heterologous cell-surface antigens. three isogenic strains of s. gordonii were used: a wild-type, a recombinant expressing the m6 protein of streptococcus pyogenes, and a recombinant expressing the e7 protein of human papillomavirus type 16 as a fusion with the m6 protein. a single dose of live bacteria was used to inoculate outbred mice ... | 1995 | 7483795 |
| use of restriction fragment polymorphism analysis of rrna genes to assign species to unknown clinical isolates of oral viridans streptococci. | this study evaluated restriction fragment length polymorphisms of rrna genes (ribotyping) for genotypic identification of 53 oral isolates classified as "streptococcus sanguis" by colony morphology. isolates were from 8-h buccal plaque on lower first permanent molars of 20 subjects. dna was digested with aatii and hybridized with digoxygenin-labeled cdna of escherichia coli 16s and 23s rrna. strains were ribotyped again with alwni or pvuii on the basis of the presence or absence of a 2,290-bp aa ... | 1994 | 7512095 |
| emergence in human dental plaque and host distribution of amylase-binding streptococci. | salivary amylase is known to bind specifically to several species of oral streptococci. to assess the importance of this interaction in bacterial colonization of the oral cavity, we determined the proportion and identity of amylase-binding bacteria (abb) in dental plaque of humans and various salivary amylase-secreting and non-secreting mammalian species. the numbers of abb in undisturbed plaque collected over time from tooth surfaces of six human volunteers or from 14 other mammalian species we ... | 1994 | 7523468 |
| comparison of amylase-binding proteins in oral streptococci. | certain species of oral streptococci bind salivary amylase to their cell surface. the patterns of amylase-binding proteins produced by a range of streptococci have been compared by ligand blotting and several characteristics of the binding proteins investigated. streptococcus gordonii was the most homogeneous species and almost all strains produced proteins migrating with molecular mass 82 kda and 20 kda. other species were more heterogeneous, releasing proteins that resolved at 87 or 82 kda and ... | 1994 | 7531664 |
| determination of 16s rrna sequences of streptococcus mitis and streptococcus gordonii and phylogenetic relationships among members of the genus streptococcus. | we determined the 16s rrna sequences of the type strains of streptococcus mitis and streptococcus gordonii and calculated the phylogenetic distances between those organisms and other members of the genus streptococcus. the viridans group streptococci were separated into five phylogenetic groups; we named these groups the anginosus group, the mitis group, the salivarius group, the bovis group, and the mutans group. s. mitis and s. gordonii clustered in the mitis group together with streptococcus ... | 1995 | 7537076 |
| saliva protein binding to layers of oral streptococci in vitro and in vivo. | this paper reports a system for measuring saliva protein binding to oral streptococci. enamel chips with layers of streptococcus gordonii blackburn or streptococcus oralis 10557 were incubated in vitro with whole saliva from eight persons. blackburn bound significantly more amylase than 10557; no strain differences were seen for lysozyme or lactoferrin. there were significant correlations between saliva and bound amylase and lactoferrin. blackburn and 10557 chips were then placed in ten subjects ... | 1995 | 7543122 |
| salivary amylase promotes adhesion of oral streptococci to hydroxyapatite. | recent studies have demonstrated that several species of oral streptococci, such as streptococcus gordonii, bind soluble salivary alpha-amylase. the goal of the present study was to determine if amylase immobilized onto a surface such as hydroxyapatite can serve as an adhesion receptor for s. gordonii. initially, human parotid saliva was fractionated on bio-gel p60, and fractions were screened for their ability to promote adhesion of s. gordonii to hydroxyapatite. fractions containing alpha-amyl ... | 1995 | 7560386 |
| sucrose-dependent accumulation of oral streptococci and their adhesion-defective mutants on saliva-coated hydroxyapatite. | the adhesion and accumulation of oral streptococci on saliva-coated hydroxyapatite was examined in strains representing species that appear in initial plaque (streptococcus sanguise fc1 and streptococcus oralis c5) and in more mature plaque (streptococcus gordonii g9b). washed cells of strains fc1 and c5 did not attach better to saliva-coated hydroxyapatite than did strain g9b, suggesting that the degree of initial adhesiveness does not alone account for the temporal appearance of these bacteria ... | 1995 | 7567067 |
| oral streptococci with genetic determinants similar to the glucosyltransferase regulatory gene, rgg. | the streptococcus gordonii challis glucosyltransferase structural gene, gtfg, is positively regulated by the upstream gene, rgg, the only described gtf regulatory determinant in oral streptococci. southern hybridization analyses indicated that rgg-like and gtfg-like determinants were present on the same hindiii fragment in strains of s. gordonii, streptococcus sanguis, and streptococcus oralis, whereas no rgg-like determinants were detected in mutans streptococci, streptococcus mitis, and strept ... | 1995 | 7591096 |
| identification of a 100-kilodalton putative coaggregation-mediating adhesin of streptococcus gordonii dl1 (challis). | streptococcus gordonii dl1 (challis) bears coaggregation-relevant surface proteins which mediate lactose-inhibitable coaggregations with other streptococci. six spontaneously occurring coaggregation-defective (cog-) mutants of wild-type strain s. gordonii dl1 unable to coaggregate with wild-type streptococcal partners were characterized. antiserum raised against wild-type cells and absorbed with cog- cells specifically blocked lactose-inhibitable coaggregations between s. gordonii dl1 and its st ... | 1995 | 7591151 |
| a tn4001 delivery system for streptococcus gordonii (challis). | the staphylococcus aureus transposon tn4001 was found to transpose in streptococcus gordonii. transposition sites appeared to be randomly distributed, and the element was stable in the absence of antibiotic selection. an increase in transposition frequency was noted when the delivery plasmid was propagated in a dam- dcm- escherichia coli host strain. the utility of tn4001 was demonstrated by the generation of lactose-negative mutants. small size, clonal stability, random transposition, and known ... | 1995 | 7597109 |
| mucosal and systemic immune responses to a recombinant protein expressed on the surface of the oral commensal bacterium streptococcus gordonii after oral colonization. | to circumvent the need to engineer pathogenic microorganisms as live vaccine-delivery vehicles, a system was developed which allowed for the stable expression of a wide range of protein antigens on the surface of gram-positive commensal bacteria. the human oral commensal streptococcus gordonii was engineered to surface express a 204-amino acid allergen from hornet venom (ag5.2) as a fusion with the anchor region of the m6 protein of streptococcus pyogenes. the immunogenicity of the m6-ag5.2 fusi ... | 1995 | 7624334 |
| use of a novel mobilizable vector to inactivate the scra gene of streptococcus sobrinus by allelic replacement. | the virulence factors of the cariogenic bacterium streptococcus sobrinus have been difficult to assess because of a lack of tools for the genetic manipulation of this organism. the construction of an escherichia coli-streptococcus shuttle vector, pdl289, that can be mobilized into s. sobrinus by the conjugative plasmid pam beta 1 was described in a previous report. the vector contains pva380-1 for replication and mobilization in streptococci, the psc101 replicon for maintenance in e. coli, a kan ... | 1995 | 7665480 |
| construction of a model secretion system for oral streptococci. | a dna fragment corresponding to the secretory domain from the streptococcus mutans gs-5 gtfb gene, which encodes the putative 38-amino-acid signal peptide of the glucosyltransferase i (gtf-i) enzyme product, has been constructed. this fragment was fused with the alpha-amylase structural gene from alkalophilic bacillus sp. strain 707. this hybrid gene as well as the intact amylase gene were introduced into an escherichia coli-streptococcus shuttle vector consisting of three components: the e. col ... | 1993 | 7689539 |
| the use of phospholipid liposomes for targeting to oral and skin-associated bacteria. | phospholipid (dipalmitoylphosphatidylcholine (dppc) plus phosphatidylinositol (pi)) proteoliposomes with surface bound lectins (succinylated concanavalin a (s con a) and wheat germ agglutinin (wga)) have been prepared covering a range of size and surface density of lectin. negatively charged phospholipid liposomes from dppc-pi mixtures covering a range of pi mole % and positively charged liposomes from dppc-cholesterol-stearylamine (sa) mixtures covering a range of sa mole % have been prepared. ... | 1994 | 7704482 |
| identification of a molecule of porphyromonas gingivalis that binds to streptococcus gordonii. | the molecules that mediate the adherence of porphyromonas gingivalis, a periodontal pathogen, to streptococcus gordonii, a commensal plaque organism, were investigated. outer membrane proteins of p. gingivalis were labelled with biotin, extracted by edta and reacted with s. gordonii cells. interactive porphyromonas components were identified by sds-page of the s. gordonii cells followed by electroblotting and visualization of the adsorbed porphyromonas molecules with streptavidin-alkaline phosph ... | 1994 | 7723662 |
| streptococci and actinomyces inhibit regrowth of streptococcus mutans on gnotobiotic rat molar teeth after chlorhexidine varnish treatment. | clinical studies suggest that the long-term suppression of mutans streptococci on tooth surfaces after intensive chlorhexidine therapy is mainly due to bacterial interference. other streptococci and also actinomyces naeslundii are proposed to inhibit regrowth of mutans streptococci after suppression by the agent. we have tested this hypothesis in gnotobiotic rats associated with streptococcus mutans alone, or associated with s. mutans and strains of streptococcus oralis, streptococcus sanguis, s ... | 1995 | 7728832 |
| adherence of candida albicans to a cell surface polysaccharide receptor on streptococcus gordonii. | candida albicans atcc 10261 and ca2 bound to cells of the oral bacteria streptococcus gordonii, streptococcus oralis, and streptococcus sanguis when these bacteria were immobilized onto microtiter plate wells, but they did not bind to cells of streptococcus mutans or streptococcus salivarius. cell wall polysaccharide was extracted with alkali from s. gordonii nctc 7869, the streptococcal species to which c. albicans bound with highest affinity, and was effective in blocking the coaggregation of ... | 1995 | 7729891 |
| degradative enzymes of oral streptococci. | members of the streptococcus sanguis group (ssg) and streptococcus milleri group (smg) were screened for their ability to produce glycosidase, arylamidase (peptidase), protease, dextranase and glycosyltransferase activities. species within each group produced unique patterns of activity. the most commonly produced glycosidases were beta-d-glucosidase, beta-d-galactosidase, n-acetyl-beta-d-glucosaminidase and n-acetyl-beta-d-galactosaminidase and the least commonly produced glycosidase activity w ... | 1995 | 7786231 |
| the history of live bacterial vaccines. | recent developments have made it possible to construct non-reverting live bacterial vaccine candidates with defined deletions of two or more genes. such vaccines have proven safe and immunogenic in human volunteers. since the virulent parent strains are only pathogenic to man (s. typhi, s. flexneri, and v. cholerae), they pose no threat to the environment. besides holding promise as efficacious vaccines for protection against typhoid fever, bacillary dysentery and cholera, the attenuated strains ... | 1995 | 7796956 |
| cloning of an enterococcus faecalis endocarditis antigen: homology with adhesins from some oral streptococci. | serum from a patient with enterococcus faecalis endocarditis was used to identify the gene efaa cloned in lambda zapii in escherichia coli. nucleotide sequence analysis revealed a 924-bp open reading frame encoding a protein with a predicted molecular weight of 34,768. the amino acid sequence of efaa shows 55 to 60% homology to a group of streptococcal proteins, fima from streptococcus parasanguis, ssab from streptococcus sanguis, scaa from streptococcus gordonii, and psaa from streptococcus pne ... | 1995 | 7822045 |
| mucin-sulphatase activity of some oral streptococci. | mucin-sulphatase activity, measured using a 35s-[so4(2-)]-labelled colonic mucin substrate, was detected in whole cells of streptococci isolated from the human oral cavity. the highest levels of sulphatase activity were found in all strains of streptococcus salivarius, streptococcus mitis and in half of the strains of streptococcus mutans tested. little or no activity was detected in 9 of the 11 streptococcus oralis strains examined, in the 4 streptococcus constellatus strains, and in the 3 stre ... | 1994 | 7850844 |
| a comparison of the microbial flora in carious dentine of clinically detectable and undetectable occlusal lesions. | it is not known whether the aetiology of occlusal hidden caries lesions (hcl) is identical to that of small visible lesions (svl). previous studies of the microflora of hcl suggest that relatively few species can be isolated. the aim of the present study was to compare the bacterial composition of dentine from 10 hcl and 17 svl in a population of children aged 8-18 years. the following bacteria were identified: actinomyces spp., mutans streptococci, streptococcus sanguis, streptococcus oralis, s ... | 1995 | 7867050 |
| cell-surface-associated polypeptides csha and cshb of high molecular mass are colonization determinants in the oral bacterium streptococcus gordonii. | the human oral bacterium streptococcus gordonii expresses, on the cell surface, two antigenically related high-molecular-mass polypeptides denoted csha and cshb, encoded by genes at separate chromosomal loci. the precursor form of csha is composed of four distinct segments: (i) a 41-amino-acid residue leader peptide, (ii) n-terminal 42-878 residues, (iii) residues 879-2417 comprising 13 repeat blocks of 101 amino acid residues and three shorter blocks, and (iv) a c-terminal anchor domain similar ... | 1994 | 7891560 |
| involvement of porphyromonas gingivalis fimbriae in adherence to streptococcus gordonii. | adherence of porphyromonas gingivalis to early plaque bacteria, such as streptococcus gordonii, is considered an important colonization mechanism. the molecules that mediate this interspecies binding have not been determined. fimbriae were prepared from p. gingivalis 33277 by mild agitation, ammonium sulfate precipitation and deae-sepharose chromatography. in a nitrocellulose blot adherence assay, purified fimbriae inhibited s. gordonii g9b-p. gingivalis 33277 binding by up to 54%. in addition, ... | 1993 | 7903442 |
| cell surface protein receptors in oral streptococci. | streptococci have a vast repertoire of adherence properties which include binding to human tissue components, epithelial cells and to other bacterial cells. these interactions are determined by the expression of cell-surface receptors some of which are species-specific. in the oral streptococci, two families of surface protein receptors with highly conserved amino acid sequences have been identified. the antigen i/ii family of polypeptides are wall-associated high molecular mass proteins (158-16 ... | 1994 | 7926661 |
| nucleotide sequence of the streptococcus gordonii pk488 coaggregation adhesin gene, scaa, and atp-binding cassette. | human oral viridans group streptococci that coaggregate with actinomyces naeslundii pk606 express surface proteins related to scaa, the coaggregation-mediating adhesin of streptococcus gordonii pk488 (r. n. andersen, n. ganeshkumar, and p. e. kolenbrander, infect. immun. 61:981-987, 1993). the nucleotide sequence of the 6,125-bp ecori insert of pra1, containing scaa, the gene encoding scaa, was determined. six open reading frames (orfs) were identified. the orientation of four orfs, two upstream ... | 1994 | 7927711 |
| an in vitro investigation of the cariogenic potential of oral streptococci. | whilst the importance of the mutans streptococci in the aetiology of dental caries is clear, a number of studies have described caries development in their absence. this investigation aimed to assess the cariogenic potential of streptococcus gordonii, strep. sanguis, strep. vestibularis and enterococcus faecalis in comparison with strep. mutans and strep. sobrinus, using a recently described in vitro model. in the presence of a 146 mm sucrose solution and powdered hydroxyapatite, each species wa ... | 1994 | 7945017 |
| calcium-binding properties of ssp-5, the streptococcus gordonii m5 receptor for salivary agglutinin. | streptococcus gordonii m5 expresses a lectin on its surface (ssp-5) which binds to human salivary agglutinin (sag). this interaction requires sialic acid residues of sag and divalent cations and may mediate the colonization of oral tissues by this organism. in this report, we show that the binding of sag to ssp-5 requires calcium and that ssp-5 is a high-affinity calcium-binding protein. sag-mediated aggregation of s. gordonii m5 was inhibited by 1 mm edta, and the restoration of aggregation occ ... | 1994 | 7960097 |
| human t-helper cell recognition of an immunodominant epitope of hiv-1 gp120 expressed on the surface of streptococcus gordonii. | our genetic system for expression of heterologous proteins on the surface of the gram-positive bacterium streptococcus gordonii was used to express a human t-helper epitope of hiv-1 envelope glycoprotein gp120. in previous work on the naive repertoire of human t-helper cells, it was shown that a 15-amino acid synthetic peptide of the hiv-1 gp120 sequence contained an immunodominant t-helper epitope. synthetic dna coding for this peptide was cloned in frame within the gene for the streptococcal s ... | 1994 | 7998415 |
| molecules of streptococcus gordonii that bind to porphyromonas gingivalis. | interbacterial binding is considered an important colonization mechanism for many of the organisms that inhabit dental plaque. porphyromonas gingivalis, a periodontal pathogen, can adhere to species that comprise early plaque, such as streptococcus gordonii. in this study, the molecules of s. gordonii g9b that mediate binding to p. gingivalis were investigated. biotinylated surface molecules of s. gordonii were extracted and mixed with p. gingivalis cells. interactive streptococcal components we ... | 1994 | 8012603 |
| the cell wall polysaccharide of streptococcus gordonii 38: structure and immunochemical comparison with the receptor polysaccharides of streptococcus oralis 34 and streptococcus mitis j22. | as part of our ongoing investigations involving lectin-mediated adhesion among oral bacteria, the receptor polysaccharide from streptococcus gordonii 38 was isolated and characterized. carbohydrate analysis of the hydrolysed s. gordonii 38 polysaccharide by high-performance anion-exchange chromatography with pulsed amperometric detection (hpaec-pad) showed galactose (gal) (2 mol), n-acetylgalactosamine (galnac) (1 mol), rhamnose (rha) (2 mol), glucose (glc) (1 mol) and galactosamine-6-phosphate ... | 1994 | 8054717 |
| inactivation of the porphyromonas gingivalis fima gene blocks periodontal damage in gnotobiotic rats. | fimbrial production by porphyromonas gingivalis was inactivated by insertion-duplication mutagenesis, using the cloned gene for the p. gingivalis major fimbrial subunit protein, fima. by several criteria, this insertion mutation rendered p. gingivalis unable to produce fimbrilin or an intact fimbrial structure. a nonfimbriated mutant, dpg3, hemagglutinated sheep erythrocytes normally and was unimpaired in the ability to coaggregate with streptococcus gordonii g9b. the cell surface hydrophobicity ... | 1994 | 8106316 |
| [endocarditis caused by streptococcus gordonii]. | | 1994 | 8155757 |
| colonization of the murine oral cavity by streptococcus gordonii. | streptococcus gordonii dl1 (challis) colonized the oral cavities of balb/c mice that lacked streptococci, enterococci, and lactobacilli (lf mice) as members of an otherwise complex digestive tract microflora. conventional mice, in comparison, were refractory to colonization by s. gordonii. mice that harbored lactobacilli but were free of streptococci and enterococci (ef mice) had a lower incidence of colonization by s. gordonii than lf animals. the lf mouse system should be useful in the study o ... | 1994 | 8168983 |
| glucosyltransferase mediates adhesion of streptococcus gordonii to human endothelial cells in vitro. | human umbilical vein endothelial cells (huvec) were used as an experimental host model to investigate the mechanism(s) of streptococcal adhesion in infective endocarditis. adhesion activity of streptococcus gordonii was maximal during the logarithmic phase of growth and was greatly reduced or eliminated by pretreatment of bacteria with heat, formaldehyde, or trypsin. at saturating numbers of streptococci, an average of 81 bacteria were bound per huvec. streptococcal adhesion was inhibited by low ... | 1994 | 8188339 |
| infectivity of a glucan synthesis-defective mutant of streptococcus gordonii (challis) in a rat endocarditis model. | streptococcus gordonii, a member of the human indigenous oral microflora, colonizes smooth tooth surfaces and contributes to dental plaque formation. although it is not recognized as being a cariogenic pathogen, it may cause endocarditis following invasion of the bloodstream. using allelic exchange mutagenesis, we have constructed a mutant of s. gordonii (challis) which is defective in its single functional glucosyltransferase gene and, hence, is unable to synthesize glucan exopolymers from sucr ... | 1993 | 8224794 |
| susceptibility of alpha-haemolytic streptococci causing endocarditis to benzylpenicillin and ten cephalosporins. | a clinical case of streptococcal endocarditis in which the isolate proved susceptible to third- but not first-generation cephalosporins prompted us to examine the susceptibility of 44 alpha-haemolytic streptococci from cases of endocarditis to ten cephalosporins and benzylpenicillin. twenty per cent of strains were resistant to penicillin, and 20% were tolerant. cefazolin, cefuroxime and cefpirome were the most active first-, second- and third-generation cephalosporins tested. other first-genera ... | 1993 | 8226418 |
| coaggregation of oral lactobacilli with streptococci from the oral cavity. | the ability of oral lactobacilli to coaggregate with streptococci and actinomycetes was investigated. of the 7 species of lactobacilli studied, only two were capable of coaggregation and the coaggregation was restricted to streptococci. lactobacillus salivarius strains (2/4) coaggregated with streptococcus salivarius, streptococcus gordonii, streptococcus crista and tufted streptococcus sanguis ii strains. lactobacillus fermentum (2/3) coaggregated with s. gordonii and s. sanguis. the coaggregat ... | 1993 | 8265207 |
| adherence of streptococcus gordonii hg 222 in the presence of saliva. | the influence of the presence of saliva from different salivary glands on the adherence of streptococcus gordonii strain hg 222 to saliva-coated polystyrene surfaces was tested. in the presence of undiluted parotid saliva or diluted whole, submandibular and sublingual saliva the adherence of hg 222 was enhanced by the formation of small aggregates on the attachment surface. in the presence of undiluted whole, submandibular and sublingual saliva large aggregates were formed and the adherence to s ... | 1993 | 8274002 |
| the cell-bound fructosyltransferase of streptococcus salivarius: the carboxyl terminus specifies attachment in a streptococcus gordonii model system. | the ftf gene, coding for the cell-bound beta-d-fructosyltransferase (ftf) of streptococcus salivarius atcc 25975, has been analyzed, and its deduced amino acid sequence has been compared with that of the secreted ftf of streptococcus mutans and the levansucrases (sacbs) of bacillus species. a unique proline-rich region detected at the c terminus of the ftf of s. salivarius preceded a hydrophobic terminal domain. this proline-rich region was shown to possess strong homology to the product of the ... | 1993 | 8331080 |
| inactivation of the gene encoding surface protein sspa in streptococcus gordonii dl1 affects cell interactions with human salivary agglutinin and oral actinomyces. | cell surface protein ssp-5 in the oral bacterium streptococcus gordonii m5 binds human salivary agglutinin in a ca(2+)-dependent reaction (d.r. demuth, e.e. golub, and d. malamud, j. biol. chem. 265:7120-7126, 1990). the region of the gene encoding an n-terminal segment of a related polypeptide (sspa) in s. gordonii dl1 (challis) was isolated following polymerase chain reaction amplification of genomic dna. the sspa gene in s. gordonii dl1 was insertionally inactivated by homologous recombinatio ... | 1993 | 8335350 |
| the comparative activity of azithromycin, macrolides and amoxycillin against streptococci in experimental infections. | since serious sequelae may follow streptococcal infections, eradication is viewed as necessary for successful therapy. studies were therefore conducted to compare the effectiveness of azithromycin with other macrolide antibiotics and amoxycillin to eliminate these organisms in experimental localized infections. in a streptococcus pneumoniae lung infection induced by transtracheal challenge, the pathogen was not recovered after therapy with azithromycin (ed50 7.9 mg/kg), while clarithromycin was ... | 1993 | 8396094 |
| expression and secretion of an arthrobacter dextranase in the oral bacterium streptococcus gordonii. | we have constructed a plasmid to express and secrete dextranase in the oral bacterium streptococcus gordonii. the dextranase gene from arthrobacter sp. strain cb-8 was linked to a promoter and a dna sequence encoding the signal peptide of streptococcus downei glucosyltransferase i (gtfi) followed by the escherichia coli rrnbt1t2 terminator and inserted in the shuttle vector pva838. s. gordonii transformed with this plasmid (pmnk-4) expressed and secreted mature arthrobacter dextranase. the trans ... | 1993 | 8406828 |
| construction of recombination-deficient strains of streptococcus gordonii by disruption of the reca gene. | degenerate oligonucleotide primers were used in a polymerase chain reaction (pcr) to amplify a region of the reca sequence of streptococcus gordonii challis. the resulting pcr fragment was cloned into the suicide vector pam6199 and introduced into strain challis, giving rise to recombination-deficient strains in which the reca gene was specifically inactivated. | 1993 | 8407809 |
| cloning and expression of the multiple sugar metabolism (msm) operon of streptococcus mutans in heterologous streptococcal hosts. | the multiple sugar metabolism (msm) operon of streptococcus mutans is responsible for the uptake and metabolism of a variety of sugars. in order to further characterize the substrate specificities of the transport system, a 12-kb region of dna containing the entire msm operon was cloned, via a novel two-step integration strategy, into the chromosomes of two heterologous streptococcal strains, streptococcus gordonii challis and streptococcus anginosus is57, as well as the chromosome of a natural ... | 1993 | 8432594 |
| cloning of the streptococcus gordonii pk488 gene, encoding an adhesin which mediates coaggregation with actinomyces naeslundii pk606. | coaggregation between streptococcus gordonii pk488 and actinomyces naeslundii pk606 is mediated by a 38-kda streptococcal protein, designated scaa. the gene, scaa, which encodes this protein has been cloned into escherichia coli. a genomic s. gordonii pk488 library (in lambda zap ii) was screened with anti-s. gordonii immunoglobulin g absorbed with s. gordonii pk1804, an isogenic coaggregation-defective mutant of strain pk488. a positive recombinant phage was isolated, and a phagemid designated ... | 1993 | 8432618 |
| dental plaque development on defined streptococcal surfaces. | coaggregations between bacterial species have been widely studied in vitro but not in the mouth. a new in vivo assay was used to measure the rate and composition of indigenous plaque formation onto bovine enamel chips covered with a continuous layer of bacteria. chips were covered with streptococcus oralis atcc 10557, which coaggregated with many oral species, or streptococcus gordonii s7, which did not coaggregate with these oral species, and placed in the mouth for 4 and 24 h. there were no di ... | 1993 | 8510979 |
| isolation and characterization of coaggregation-defective (cog-) mutants of streptococcus gordonii dl1 (challis). | streptococcus gordonii dl1 (challis) bears coaggregation-mediating surface adhesins which recognize galactoside-containing surface polysaccharides on streptococcus oralis 34, streptococcus oralis c104, and streptococcus sm pk509. fifty-nine spontaneously-occurring coaggregation-defective (cog-) mutants of s. gordonii dl1 unable to coaggregate with partner streptococci were isolated. six representative cog- mutants were characterized by their coaggregation properties with four actinomyces naeslun ... | 1995 | 8519477 |
| interactions of candida albicans with bacteria and salivary molecules in oral biofilms. | the yeast candida albicans coaggregates with a variety of streptococcal species, an interaction that may promote oral colonization by yeast cells. c. albicans and candida tropicalis are the yeasts most frequently isolated from the human oral cavity and our data demonstrate that both these species bind to streptococcus gordonii nctc 7869 while two other candida species (candida krusei and candida kefyr) do not. adherence of c. albicans was greatest when the yeast had been grown at 30 degrees c to ... | 1995 | 8519479 |
| detection of binding of denatured salivary alpha-amylase to streptococcus sanguis. | native alpha-amylase, either solubilized, or immobilized and tested with an overlay immunotechnique, was bound in a species-specific manner to streptococcus mitis and to one of the streptococcus gordonii strains. however, only insignificant amounts of alpha-amylase were bound to streptococcus sanguis and all other strains tested. when alpha-amylase was denatured before immobilization, streptococcus sanguis bound strongly to the protein while binding of other strains was insignificant. | 1995 | 8526808 |
| streptococcus salivarius urease: genetic and biochemical characterization and expression in a dental plaque streptococcus. | the hydrolysis of urea by urease enzyme of oral bacteria is believed to have a major impact on oral microbial ecology and to be intimately involved in oral health and diseases. to begin to understand the biochemistry and genetics of oral ureolysis, a study of the urease of streptococcus salivarius, a highly ureolytic organism which is present in large numbers on the soft tissues of the oral cavity, has been initiated. by using as a probe a 0.6-kpb internal fragment of the s. salivarius 57.i urec ... | 1996 | 8550211 |
| a binding-lipoprotein-dependent oligopeptide transport system in streptococcus gordonii essential for uptake of hexa- and heptapeptides. | cells of the oral bacterium streptococcus gordonii express three cytoplasmic membrane-bound lipoproteins with apparent molecular masses of 76 to 78 kda that are the products of three genes (designated hppa, hppg, and hpph). the lipoproteins are immunologically cross-reactive, contain 60% or more identical amino acid residues, and are highly similar to the amia, alia (plpa), and alib substrate-binding protein components of an oligopeptide permease in streptococcus pneumoniae. insertional inactiva ... | 1996 | 8550445 |
| 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 ... | 1996 | 8550516 |
| development of a heterodimer plasmid system for the introduction of heterologous genes into streptococci. | we have previously constructed a model secretion system for oral streptococci using the secretory domain of the streptococcus mutans gs-5 gtfb gene. as an initial step in developing systems for secreting protein fusions containing a glucan-binding polypeptide from streptococci, a dna fragment corresponding to the glucan-binding domain (gbd) of the glucosyltransferase-s enzyme from strain gs-5 was fused to the gtfb secretory domain. however, it was not possible to clone the hybrid gene into esche ... | 1995 | 8559806 |
| dna-binding activities in streptococcus gordonii: identification of a receptor-nickase and a histonelike protein. | extraction of streptococcus gordonii cells with the mild chaotropic agent, licl, drastically decreased dna transforming ability, had little effect on viability, and released both dna nicking and binding activities. both activities were mg2+ and ca2+ independent and were not competence specific. southwestern blot analysis of the extract identified putative surface proteins of 56 kda and 68 kda in strain challis and wicky, respectively. extracts also contained a 10-kda dna-binding protein, designa ... | 1996 | 8574134 |
| multiple phase variation in haemolytic, adhesive and antigenic properties of streptococcus gordonii. | streptococcus gordonii gave rise to beta-haemolytic variants (bhp+ for beta-haemolysin production) at frequencies of 10(-4)-10(-3) on agar medium containing washed horse erythrocytes. bhp+ variants reverted to the wild-type alpha-haemolytic phenotype (bhp-) at the same frequencies. there was a significant probability (> or = 0.1) that phase variation in bhp and phase variation in the previously described spp (sucrose promoted phenotype) would occur concomitantly, but there was no correlation bet ... | 1996 | 8581164 |
| molecular analysis of streptococcus gordonii glucosyltransferase phase variants. | | 1995 | 8586195 |
| lipoprotein receptors in oral streptococci. | streptococcus gordonii produces cell-surface lipopolypeptides that have been implicated in the determination of cell adherence and aggregation properties. sara lipopolypeptide produced by s. gordonii is highly similar to the oligopeptide-binding protein amia in streptococcus pneumoniae and to the oppa and spooka oligopeptide-binding proteins in bacillus subtilis. insertional mutagenesis was used to inactivate the genes encoding sara (76kda) lipoprotein and a related 78-kda lipoprotein denoted sa ... | 1995 | 8586198 |
| characterization of csha, a high molecular mass adhesin of streptococcus gordonii. | | 1995 | 8586204 |
| cloning and sequence analysis of thymidine kinase from the oral bacterium streptococcus gordonii. | thymidine kinase is an important enzyme in the pyrimidine nucleotide salvage pathway and catalyzes the formation of thymidylate from thymidine using atp as a phosphate donor. the gene encoding thymidine kinase of the oral bacterium streptococcus gordonii was cloned and the nucleotide sequence determined. the inferred amino acid sequence of thymidine kinase (191 amino acids) exhibited 43% identity with type ii thymidine kinase from escherichia coli. the s. gordonii thymidine kinase expressed in e ... | 1996 | 8598265 |
| the effect of sodium hypochlorite on potential pathogenic traits of candida albicans and other candida species. | strains of candida albicans, candida krusei, candida kefyr, candida tropicalis, candida parapsilosis and candida guilliermondii were grown in the presence or absence of concentrations of sodium hypochlorite below the minimal inhibitory concentration and tested for a range of characteristics that may be associated with pathogenicity. sodium hypochlorite is used routinely in hospitals in australia for disinfection procedures, and these experiments were designed to assess the efficacy of hypochlori ... | 1995 | 8602340 |
| a host-vector system for heterologous gene expression in streptococcus gordonii. | we have developed a host-vector system for heterologous expression in streptococcus gordonii (sg) challis (formerly streptococcus sanguis), a commensal bacterium of the human oral cavity. the system is based on (i) integration of plasmid insertion vectors into the chromosome of specially engineered recipient hosts, and (ii) the use of the m6-protein-encoding gene (emm6) as a partner for construction of translational gene fusions. m6 is a streptococcal surface protein already proven useful as a f ... | 1996 | 8635755 |
| comparison of nmr and molecular modeling results for a rigid and a flexible oligosaccharide. | three-bond heteronuclear coupling constants (3jch) are extremely useful in describing flexible models for oligosaccharides. we show that antiphase methods for measuring 3jch in oligosaccharides have limited reliability but that the coupling constants can be reliably measured in natural abundance by quantitative j-correlation methods. interpretation of 3jch data for a pentasaccharide (lacto-n-fuco-pentaose 2) from human milk are consistent with a rigid model for the lewis(a) trisaccharide epitope ... | 1996 | 8724136 |
| tandem genes encode cell-surface polypeptides sspa and sspb which mediate adhesion of the oral bacterium streptococcus gordonii to human and bacterial receptors. | the highly conserved antigen i/ii family of polypeptides produced by oral streptococci are believed to be colonization determinants and may mediate adhesion of bacterial cells to salivary glycoproteins absorbed to cells and tissues in the human oral cavity. streptococcus gordonii is shown to express, on the cell surface, two antigen i/ii polypeptides designated sspa and sspb (formerly ssp-5) that are the products of tandemly arranged chromosomal genes. the structure and arrangement of these gene ... | 1996 | 8733238 |
| the alpha-hemolysin of streptococcus gordonii is hydrogen peroxide. | the alpha-hemolysin of viridans group streptococci, which causes greening of intact erythrocytes, is a potential virulence factor as well as an important criterion for the laboratory identification of these bacteria; however, it has never been purified and characterized. the alpha-hemolysin of streptococcus gordonii ch1 caused characteristic shifts in the a403, a430, a578, and a630 of sheep hemoglobin. a spectrophotometric assay was developed and used to monitor purification of alpha-hemolysin d ... | 1996 | 8751938 |
| natural transformation of streptococcus crista. | over the years streptococcus gordonii (sanguis) challis has become the workhorse of genetic manipulations for the sanguis group of oral streptococci. this is because strain challis was shown in early studies to be highly naturally competent for transformation. however, challis is not usually the most appropriate strain to use in studies which focus on oral microbial adherence. we report that other members of the newly reorganized sanguis group, particularly within the species s. crista, display ... | 1996 | 8807795 |
| rgg is a positive transcriptional regulator of the streptococcus gordonii gtfg gene. | the streptococcus gordonii (challis) glucosyltransferase-encoding determinant gtfg is regulated by the product of the adjacent gene rgg. results of analyses described here showed that in both s. gordonii and escherichia coli rgg is a positive transcriptional regulator of glucosyltransferase expression. in addition, the transcriptional start sites of both gtfg and rgg were determined. | 1996 | 8824637 |