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Deciphering Streptococcal Biofilms. Microorganisms 2020; 8:microorganisms8111835. [PMID: 33233415 PMCID: PMC7700319 DOI: 10.3390/microorganisms8111835] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 11/10/2020] [Accepted: 11/17/2020] [Indexed: 12/19/2022] Open
Abstract
Streptococci are a diverse group of bacteria, which are mostly commensals but also cause a considerable proportion of life-threatening infections. They colonize many different host niches such as the oral cavity, the respiratory, gastrointestinal, and urogenital tract. While these host compartments impose different environmental conditions, many streptococci form biofilms on mucosal membranes facilitating their prolonged survival. In response to environmental conditions or stimuli, bacteria experience profound physiologic and metabolic changes during biofilm formation. While investigating bacterial cells under planktonic and biofilm conditions, various genes have been identified that are important for the initial step of biofilm formation. Expression patterns of these genes during the transition from planktonic to biofilm growth suggest a highly regulated and complex process. Biofilms as a bacterial survival strategy allow evasion of host immunity and protection against antibiotic therapy. However, the exact mechanisms by which biofilm-associated bacteria cause disease are poorly understood. Therefore, advanced molecular techniques are employed to identify gene(s) or protein(s) as targets for the development of antibiofilm therapeutic approaches. We review our current understanding of biofilm formation in different streptococci and how biofilm production may alter virulence-associated characteristics of these species. In addition, we have summarized the role of surface proteins especially pili proteins in biofilm formation. This review will provide an overview of strategies which may be exploited for developing novel approaches against biofilm-related streptococcal infections.
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Souza JGS, Bertolini M, Thompson A, Mansfield JM, Grassmann AA, Maas K, Caimano MJ, Barao VAR, Vickerman MM, Dongari-Bagtzoglou A. Role of glucosyltransferase R in biofilm interactions between Streptococcus oralis and Candida albicans. THE ISME JOURNAL 2020; 14:1207-1222. [PMID: 32042100 PMCID: PMC7174356 DOI: 10.1038/s41396-020-0608-4] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 01/08/2020] [Accepted: 01/30/2020] [Indexed: 02/08/2023]
Abstract
Streptococcal glucosyltransferases (Gtf) synthesize α-glucan exopolymers which contribute to biofilm matrix. Streptococcus oralis interacts with the opportunistic pathogen Candida albicans to form hypervirulent biofilms. S. oralis 34 has a single gtf gene (gtfR). However, the role of gtfR in single and mixed species biofilms with C. albicans has never been examined. A gtfR deletion mutant, purified GtfR, and recombinant GtfR glucan-binding domain were tested in single and mixed biofilms on different substrata in vitro. A mouse oral infection model was also used. We found that in single species biofilms growing with sucrose on abiotic surfaces S. oralis gtfR increased biofilm matrix, but not bacterial biomass. In biofilms with C. albicans, S. oralis encoding gtfR showed increased bacterial biomass on all surfaces. C. albicans had a positive effect on α-glucan synthesis, and α-glucans increased C. albicans accretion on abiotic surfaces. In single and mixed infection of mice receiving sucrose S. oralis gtfR enhanced mucosal burdens. However, sucrose had a negative impact on C. albicans burdens and reduced S. oralis burdens in co-infected mice. Our data provide new insights on the GtfR-mediated interactions between the two organisms and the influence of biofilm substratum and the mucosal environment on these interactions.
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Affiliation(s)
- João Gabriel Silva Souza
- Department of Oral Health and Diagnostic Sciences, University of Connecticut School of Dental Medicine, Farmington, CT, USA
- Department of Prosthodontics and Periodontology, Piracicaba Dental School, University of Campinas (UNICAMP), Piracicaba, São Paulo, Brazil
| | - Martinna Bertolini
- Department of Oral Health and Diagnostic Sciences, University of Connecticut School of Dental Medicine, Farmington, CT, USA
| | - Angela Thompson
- Department of Oral Health and Diagnostic Sciences, University of Connecticut School of Dental Medicine, Farmington, CT, USA
| | - Jillian M Mansfield
- Department of Oral Biology, School of Dental Medicine, University at Buffalo, Buffalo, NY, USA
| | - André Alex Grassmann
- Departments of Medicine, Pediatrics and Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, CT, USA
| | - Kendra Maas
- Microbial Analysis, Resources, and Services Core, University of Connecticut, Storrs, CT, USA
| | - Melissa J Caimano
- Departments of Medicine, Pediatrics and Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, CT, USA
| | - Valentim Adelino Ricardo Barao
- Department of Prosthodontics and Periodontology, Piracicaba Dental School, University of Campinas (UNICAMP), Piracicaba, São Paulo, Brazil
| | - M Margaret Vickerman
- Department of Oral Biology, School of Dental Medicine, University at Buffalo, Buffalo, NY, USA.
| | - Anna Dongari-Bagtzoglou
- Department of Oral Health and Diagnostic Sciences, University of Connecticut School of Dental Medicine, Farmington, CT, USA.
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Hall JW, Lima BP, Herbomel GG, Gopinath T, McDonald L, Shyne MT, Lee JK, Kreth J, Ross KF, Veglia G, Herzberg MC. An intramembrane sensory circuit monitors sortase A-mediated processing of streptococcal adhesins. Sci Signal 2019; 12:12/580/eaas9941. [PMID: 31064885 DOI: 10.1126/scisignal.aas9941] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Bacterial adhesins mediate adhesion to substrates and biofilm formation. Adhesins of the LPXTG family are posttranslationally processed by the cell membrane-localized peptidase sortase A, which cleaves the LPXTG motif. This generates a short C-terminal peptide (C-pep) that remains in the cell membrane, whereas the mature adhesin is incorporated into the cell wall. Genes encoding adhesins of the oral bacterium Streptococcus gordonii were differentially expressed depending on whether the bacteria were isolated from saliva or dental plaque and appeared to be coordinately regulated. Deletion of sspA and sspB (sspAB), both of which encode LPXTG-containing adhesins, unexpectedly enhanced adhesion and biofilm formation. C-peps produced from a model LPXTG-containing adhesin localized to the cell membrane and bound to and inhibited the intramembrane sensor histidine kinase SGO_1180, thus preventing activation of the cognate response regulator SGO_1181. The absence of SspAB C-peps induced the expression of the scaCBA operon encoding the lipoprotein adhesin ScaA, which was sufficient to preserve and even enhance biofilm formation. This C-pep-driven regulatory circuit also exists in pathogenic streptococci and is likely conserved among Gram-positive bacteria. This quality control mechanism ensures that the bacteria can form biofilms under diverse environmental conditions and may play a role in optimizing adhesion and biofilm formation.
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Affiliation(s)
- Jeffrey W Hall
- Department of Biological and Diagnostic Sciences, University of Minnesota, Minneapolis, MN 55455, USA
| | - Bruno P Lima
- Department of Biological and Diagnostic Sciences, University of Minnesota, Minneapolis, MN 55455, USA
| | | | - Tata Gopinath
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - LeAnna McDonald
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Michael T Shyne
- Biostatistical Design and Analysis Center (BDAC), Clinical and Translational Science Institute, University of Minnesota, Minneapolis, MN 55455, USA
| | - John K Lee
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Jens Kreth
- Department of Restorative Dentistry, Oregon Health and Science University, Portland, OR 97239, USA
| | - Karen F Ross
- Department of Biological and Diagnostic Sciences, University of Minnesota, Minneapolis, MN 55455, USA
| | - Gianluigi Veglia
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.,Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Mark C Herzberg
- Department of Biological and Diagnostic Sciences, University of Minnesota, Minneapolis, MN 55455, USA.
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Taking the starch out of oral biofilm formation: molecular basis and functional significance of salivary α-amylase binding to oral streptococci. Appl Environ Microbiol 2012; 79:416-23. [PMID: 23144140 DOI: 10.1128/aem.02581-12] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
α-Amylase-binding streptococci (ABS) are a heterogeneous group of commensal oral bacterial species that comprise a significant proportion of dental plaque microfloras. Salivary α-amylase, one of the most abundant proteins in human saliva, binds to the surface of these bacteria via specific surface-exposed α-amylase-binding proteins. The functional significance of α-amylase-binding proteins in oral colonization by streptococci is important for understanding how salivary components influence oral biofilm formation by these important dental plaque species. This review summarizes the results of an extensive series of studies that have sought to define the molecular basis for α-amylase binding to the surface of the bacterium as well as the biological significance of this phenomenon in dental plaque biofilm formation.
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Clewell DB. Tales of conjugation and sex pheromones: A plasmid and enterococcal odyssey. Mob Genet Elements 2011; 1:38-54. [PMID: 22016844 PMCID: PMC3190283 DOI: 10.4161/mge.1.1.15409] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Accepted: 03/03/2011] [Indexed: 12/11/2022] Open
Abstract
This review covers highlights of the author's experience becoming and working as a plasmid biologist. The account chronicles a progression from studies of ColE1 DNA in Escherichia coli to Gram-positive bacteria with an emphasis on conjugation in enterococci. It deals with gene amplification, conjugative transposons and sex pheromones in the context of bacterial antibiotic resistance.
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Affiliation(s)
- Don B Clewell
- Biologic and Materials Sciences; School of Dentistry and Microbiology and Immunology; Medical School; The University of Michigan; Ann Arbor, MI USA
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McNab R, Jenkinson HF. Aggregation-deficient Mutants of Streptococcus gordonii Channon Altered in Production of Cell-surface Polysaccharide and Proteins. MICROBIAL ECOLOGY IN HEALTH AND DISEASE 2009. [DOI: 10.3109/08910609209141549] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- R. McNab
- Department of Oral Biology and Oral Pathology, University of Otago, PO Box 647, Dunedin, New Zealand
| | - H. F. Jenkinson
- Department of Oral Biology and Oral Pathology, University of Otago, PO Box 647, Dunedin, New Zealand
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Tanzer JM, Thompson AM, Grant LP, Vickerman MM, Scannapieco FA. Streptococcus gordonii's sequenced strain CH1 glucosyltransferase determines persistent but not initial colonization of teeth of rats. Arch Oral Biol 2007; 53:133-40. [PMID: 17961499 DOI: 10.1016/j.archoralbio.2007.08.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2007] [Revised: 08/02/2007] [Accepted: 08/03/2007] [Indexed: 11/17/2022]
Abstract
OBJECTIVE Extracellular glucan synthesis from sucrose by Streptococcus gordonii, a major dental plaque biofilm bacterium, is assumed important for colonization of teeth; but this hypothesis is un-tested in vivo. METHODS To do so, we studied an isogenic glucosyltransferase (Gtf)-negative mutant (strain AMS12, gtfG(-)) of S. gordonii sequenced wild type (WT, strain Challis CH1, gtfG(+)), comparing their in vitro abilities to grow in the presence of glucose and sucrose and, in vivo, to colonize and persist on teeth and induce caries in rats. Weanling rats of two breeding colonies, TAN:SPFOM(OM)BR and TAN:SPFOM(OMASF)BR, eating high sucrose diet, were inoculated with either the WT (gtfG(+)), its isogenic gtfG(-) mutant, or reference strains of Streptococcus mutans. Control animals were not inoculated. RESULTS In vitro, the gtfG(-) strain grew at least as rapidly in the presence of sucrose as its WT gtfG(+) progenitor, but formed soft colonies on sucrose agar, consistent with its lack of insoluble glucan synthesis. It also had a higher growth yield due apparently to its inability to channel carbon flow into extracellular glucan. In vivo, the gtfG(-) mutant initially colonized as did the WT but, unlike the WT, failed to persist on the teeth as shown over time. By comparison to three S. mutans strains, S. gordonii WT, despite its comparable ecological success on the teeth, was associated with only modest caries induction. Failure of the gtfG(-) mutant to persistently colonize was associated with slight diminution of caries scores by comparison with its gtfG(+) WT. CONCLUSIONS Initial S. gordonii colonization does not depend on Gtf-G synthesis; rather, Gtf-G production determines S. gordonii's ability to persist on the teeth of sucrose-fed rats. S. gordonii appears weakly cariogenic by comparison with S. mutans reference strains.
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Affiliation(s)
- J M Tanzer
- Division of Oral Medicine, Department of Oral Health and Diagonistic Science, University of Connecticut Health Center, Farmington, CT 06030-1605, USA.
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Stinson MW, Alder S, Kumar S. Invasion and killing of human endothelial cells by viridans group streptococci. Infect Immun 2003; 71:2365-72. [PMID: 12704106 PMCID: PMC153257 DOI: 10.1128/iai.71.5.2365-2372.2003] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2002] [Revised: 12/18/2002] [Accepted: 01/29/2003] [Indexed: 11/20/2022] Open
Abstract
Colonization of the cardiovascular endothelium by viridans group streptococci can result in infective endocarditis and possibly atherosclerosis; however, the mechanisms of pathogenesis are poorly understood. We investigated the ability of selected oral streptococci to infect monolayers of human umbilical vein endothelial cells (HUVEC) in 50% human plasma and to produce cytotoxicity. Planktonic Streptococcus gordonii CH1 killed HUVEC over a 5-h period by peroxidogenesis (alpha-hemolysin) and by acidogenesis but not by production of protein exotoxins. HUVEC were protected fully by addition of supplemental buffers and bovine liver catalase to the culture medium. Streptococci were also found to invade HUVEC by an endocytic mechanism that was dependent on polymerization of actin microfilaments and on a functional cytoskeleton, as indicated by inhibition with cytochalasin D and nocodazole. Electron microscopy revealed streptococci attached to HUVEC surfaces via numerous fibrillar structures and bacteria in membrane-encased cytoplasmic vacuoles. Following invasion by S. gordonii CH1, HUVEC monolayers showed 63% cell lysis over 4 h, releasing 64% of the total intracellular bacteria into the culture medium; however, the bacteria did not multiply during this time. The ability to invade HUVEC was exhibited by selected strains of S. gordonii, S. sanguis, S. mutans, S. mitis, and S. oralis but only weakly by S. salivarius. Comparison of isogenic pairs of S. gordonii revealed a requirement for several surface proteins for maximum host cell invasion: glucosyltransferase, the sialic acid-binding protein Hsa, and the hydrophobicity/coaggregation proteins CshA and CshB. Deletion of genes for the antigen I/II adhesins, SspA and SspB, did not affect invasion. We hypothesize that peroxidogenesis and invasion of the cardiovascular endothelium by viridans group streptococci are integral events in the pathogenesis of infective endocarditis and atherosclerosis.
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Affiliation(s)
- Murray W Stinson
- Center for Microbial Pathogenesis, Department of Microbiology, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, New York 14214, USA.
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Vickerman MM, Mather NM, Minick PE, Edwards CA. Initial characterization of the Streptococcus gordonii htpX gene. ORAL MICROBIOLOGY AND IMMUNOLOGY 2002; 17:22-31. [PMID: 11860552 DOI: 10.1046/j.0902-0055.2001.00000.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Examination of the Streptococcus gordonii chromosomal region, which lies immediately upstream of the glucosyltransferase positive regulatory determinant rgg, revealed two open reading frames. Based on nucleotide sequences, these genes were similar to the Listeria monocytogenes lemA gene, which is involved in antigen presentation, and the Escherichia coli htpX heat shock gene, which has an unknown function. Northern hybridization analysis indicated that S. gordonii lemA and htpX genes were associated with a ca. 1.7-kb polycistronic transcript. Although levels of the lemA/htpX transcript did not increase in response to heat to levels seen with dnaK controls, insertional inactivation of htpX resulted in changes in adhesiveness, cellular morphology and detergent-extractable surface antigens in cells grown at 41 degrees C, implying that htpX may be involved in surface protein expression. Insertional inactivation of lemA and htpX indicated that, despite their proximity to rgg and the structural gene, gtfG, these upstream genes do not affect S. gordonii glucosyltransferase activity.
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Affiliation(s)
- M M Vickerman
- Department of Oral Surgery and Hospital Dentistry, School of Dentistry, Indiana University, 1121 West Michigan Street, Indianapolis, IN 46202, USA
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O'Neal PV, Brown N, Munro C. Physiologic factors contributing to a transition in oral immunity among mechanically ventilated adults. Biol Res Nurs 2002; 3:132-9. [PMID: 12003441 DOI: 10.1177/1099800402003003003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Ventilator-associated pneumonia (VAP), a specific type of nosocomial pneumonia, occurs in approximately 21% of patients in intensive care, and the mortality can be as high as 71%. VAP causes considerable mortality and morbidity, and it exponentially increases health care costs. The incidence of VAP is associated with oropharyngeal colonization of gram-negative bacteria. Within 48 h of hospital admission, the composition of the oropharyngeal flora of critically ill patients undergoes a change from the usual gram-positive streptococci and dental pathogens to a predominant gram-negative flora that includes more virulent organisms, which predispose patients to VAP. Identification and understanding of this oral transition from gram-positive to predominantly gram-negative flora may assist health care professionals in differentiating among oral immune markers that suggest compromised immunity. The purpose of this article is to provide a review of the literature that promotes an understanding of current knowledge about the transition of oral immunity in mechanically ventilated patients.
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Affiliation(s)
- Pamela V O'Neal
- Gordon College, University System of Georgia, Barnesville 30204, USA.
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Tanzer JM, Baranowski LK, Rogers JD, Haase EM, Scannapieco FA. Oral colonization and cariogenicity of Streptococcus gordonii in specific pathogen-free TAN:SPFOM(OM)BR rats consuming starch or sucrose diets. Arch Oral Biol 2001; 46:323-33. [PMID: 11269866 DOI: 10.1016/s0003-9969(00)00126-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The significance of Streptococcus gordonii in dental caries is undefined, as is that of other alpha-amylase-binding bacteria (ABB) commonly found in the mouth. To clarify the ecological and cariological roles of S. gordonii our specific pathogen-free Osborne-Mendel rats, TAN:SPFOM(OM)BR, were fed either diet 2000 (containing 56% confectioner's sugar, most of which is sucrose) or diet 2000CS (containing 56% cornstarch, in lieu of confectioner's sugar) and inoculated with S. gordonii strains. Uninoculated rats were free of both indigenous mutans streptococci (MS) and ABB, including S. gordonii, as shown by culture on mitis salivarius and blood agars of swabs and sonicates of dentitions after weanlings had consumed these diets for 26 days. ABB were detected by radiochemical assay using [125I]-amylase reactive to alpha-amylase-binding protein characteristic of the surface of S. gordonii and other ABB. No ABB were detected (detection limit < 1 colony-forming units in 10(6) colony-forming units). Thus the TAN:SPFOM(OM)BR colony presents a 'clean animal model' for subsequent study. Consequently, S. gordonii strains Challis or G9B were used to inoculate weanling rat groups consuming either the high-sucrose diet 2000 or the cornstarch diet 2000CS. Two additional groups fed each of these diets remained unioculated. Recoveries of inoculants were tested 12 and 26 days later by oral swabs and sonication of the molars of one hemimandible of each animal, respectively. Uninoculated animals were reconfirmed to be free of ABB and mutans streptococci, but inoculated ones eating diet 2000CS had S. gordonii recoveries of 1-10% or, if eating diet 2000, 10-30% of total colony-farming units in sonicates. There were no statistically significant differences among the inoculated and uninoculated animal groups' caries scores when they ate the cornstarch diet. Lesion scores for sucrose-eating rats were, however, from 2.4-5.1-fold higher than for cornstarch-eating rats, P < 0.001, and were still higher if animals had been inoculated with either Challis (1.41-fold) or G9B (1.64-fold), than if uninoculated, both P < 0.001, so long as the rats ate the sucrose diet. Therefore, TAN:SPFOM(OM)BR rats do not harbour ABB or S. gordonii but can be colonized by S. gordonii. Colonization levels of S. gordonii on the teeth are higher in the presence of high sucrose than with high starch-containing diets. Caries scores are augmented by sucrose compared with starch, and are further augmented by S gordonii colonization. S. gordonii is thus cariologically significant in the presence of sucrose, at least in this rat.
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Affiliation(s)
- J M Tanzer
- Department of Oral Diagnosis, School of Dental Medicine, University of Connecticut Health Center, Farmington, CT 06030-1605, USA.
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Abstract
Dental plaque is a complex biofilm that accumulates on the hard tissues (teeth) in the oral cavity. Although over 500 bacterial species comprise plaque, colonization follows a regimented pattern with adhesion of initial colonizers to the enamel salivary pellicle followed by secondary colonization through interbacterial adhesion. A variety of adhesins and molecular interactions underlie these adhesive interactions and contribute to plaque development and ultimately to diseases such as caries and periodontal disease.
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Affiliation(s)
- B Rosan
- Department of Microbiology, School of Dental Medicine, University of Pennsylvania, Philadelphia 19104, USA
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Loo CY, Corliss DA, Ganeshkumar N. Streptococcus gordonii biofilm formation: identification of genes that code for biofilm phenotypes. J Bacteriol 2000; 182:1374-82. [PMID: 10671461 PMCID: PMC94426 DOI: 10.1128/jb.182.5.1374-1382.2000] [Citation(s) in RCA: 361] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Viridans streptococci, which include Streptococcus gordonii, are pioneer oral bacteria that initiate dental plaque formation. Sessile bacteria in a biofilm exhibit a mode of growth that is distinct from that of planktonic bacteria. Biofilm formation of S. gordonii Challis was characterized using an in vitro biofilm formation assay on polystyrene surfaces. The same assay was used as a nonbiased method to screen isogenic mutants generated by Tn916 transposon mutagenesis for defective biofilm formation. Biofilms formed optimally when bacteria were grown in a minimal medium under anaerobic conditions. Biofilm formation was affected by changes in pH, osmolarity, and carbohydrate content of the growth media. Eighteen biofilm-defective mutants of S. gordonii Challis were identified based on Southern hybridization with a Tn916-based probe and DNA sequences of the Tn916-flanking regions. Molecular analyses of these mutants showed that some of the genes required for biofilm formation are involved in signal transduction, peptidoglycan biosynthesis, and adhesion. These characteristics are associated with quorum sensing, osmoadaptation, and adhesion functions in oral streptococci. Only nine of the biofilm-defective mutants had defects in genes of known function, suggesting that novel aspects of bacterial physiology may play a part in biofilm formation. Further identification and characterization of biofilm-associated genes will provide insight into the molecular mechanisms of biofilm formation of oral streptococci.
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Affiliation(s)
- C Y Loo
- Department of Molecular Genetics, The Forsyth Institute, Boston, Massachusetts 02115, USA
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Vickerman MM, Clewell DB. Deletions in the carboxyl-terminal region of Streptococcus gordonii glucosyltransferase affect cell-associated enzyme activity and sucrose-associated accumulation of growing cells. Appl Environ Microbiol 1997; 63:1667-73. [PMID: 9143100 PMCID: PMC168460 DOI: 10.1128/aem.63.5.1667-1673.1997] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The single glucosyltransferase (GTF) of Streptococcus gordonii Challis CH1 makes alpha 1,3- and alpha 1,6-linked glucans from sucrose. The GTF carboxyl-terminal region has six direct repeats thought to be involved in glucan binding. Strains with defined mutations in this region have been described recently (M. M. Vickerman, M. C. Sulavik, P. E. Minick, and D. B. Clewell, Infect. Immun. 64:5117-5128, 1996). Strain CH107 GTF has three internal direct repeats deleted; the 59 carboxyl-terminal amino acids are identical to those of the parental strain. This deletion resulted in decreased enzyme activity but did not affect the amount of cell-associated GTF protein. The GTFs of strains CH2RPE and CH4RPE have six and eight direct repeats, respectively, but are both missing the 14 carboxyl-terminal amino acids. Strain CH2RPE had significantly decreased levels of cell-associated GTF; this decrease was not obviated by the increased number of direct repeats in strain CH4RPE. Thus, the carboxyl-terminal amino acids appeared to influence the amount of cell-associated GTF more than the direct repeats. The qualitative and quantitative differences in the GTFs did not affect the abilities of these strains to accumulate on hydroxyapatite beads in the absence of sucrose. However, when sucrose was added as a substrate for GTF, the mutant strains were unable to accumulate on these surfaces to the same extent as the parent. These differences in sucrose-associated accumulation may be due to changes in the nature of the glucans produced by the different enzymes and/or cohesive interactions between these glucans and the GTF on the surfaces of the growing streptococci.
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Affiliation(s)
- M M Vickerman
- Department of Microbiology and Immunology, School of Medicine, University of Michigan, Ann Arbor 48109, USA.
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Vickerman MM, Jones GW, Clewell DB. Molecular analysis of representative Streptococcus gordonii Spp phase variants reveals no differences in the glucosyltransferase structural gene, gtfG. ORAL MICROBIOLOGY AND IMMUNOLOGY 1997; 12:82-90. [PMID: 9227131 DOI: 10.1111/j.1399-302x.1997.tb00622.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Streptococcus gordonii glucosyltransferase polymerizes sucrose to form glucans, which confer a hard, sucrose-promoted phenotype (Spp+) to colonies on sucrose agar plates. The glucosyltransferase structural gene, gtfG, is positively regulated by the upstream determinant, rgg. Strain Challis undergoes a spontaneous, reversible phase variation between high (Spp+) and low (Spp-) levels of glucosyltransferase activity. Representative strains were examined to gain insights into the basis of glucosyltransferase phase variation. Western blots indicated that the level of glucosyltransferase activity was related to the amount of extracellular glucosyltransferase protein produced by Spp- and Spp+ strains. The nucleotide sequence of rgg and gtfG of the Spp- strain CH97 was found to be identical to that of the Spp+ parent, indicating that DNA differences in these regions are not the basis for glucosyltransferase phase variation. Indeed, 13C-NMR spectroscopy suggested that glucans synthesized by strain CH97 glucosyltransferase were similar to those synthesized by glucosyltransferase of the Spp+ parental strain, indicating a quantitative rather than qualitative change. However, one Spp- strain, CH1C1, had a point mutation in rgg; replacement of the parent rgg with the CH1C1 allele resulted in decreased levels of glucosyltransferase protein and activity. The results indicate that glucosyltransferase phase variation can occur in more than one way, and suggest that glucosyltransferase regulation may involve distally located regulatory gene(s) that affect rgg and/or gtfG expression.
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Affiliation(s)
- M M Vickerman
- Department of Microbiology and Immunology, School of Medicine, Ann Arbor 48109-0620, USA
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Vickerman MM, Sulavik MC, Nowak JD, Gardner NM, Jones GW, Clewell DB. Nucleotide sequence analysis of the Streptococcus gordonii glucosyltransferase gene, gtfG. DNA SEQUENCE : THE JOURNAL OF DNA SEQUENCING AND MAPPING 1997; 7:83-95. [PMID: 9063645 DOI: 10.3109/10425179709020155] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Streptococcus gordonii has an extracellular glucosyltransferase (GTF) that polymerizes the glucose moiety of sucrose to form both water-soluble and water-insoluble glucans. Whereas multiple gtf genes have been identified in strains of mutans streptococci and Streptococcus salivarius, a single gene, designated gtfG, encodes the GTF of S. gordonii Challis. gtfG is also unique among the characterized gtfs in that it has a described regulatory determinant, rgg. Furthermore, the GTF activity in S. gordonii undergoes reversible phase variation between high and low levels. In order to gain insight into this novel GTF system, the nucleotide sequence of gtfG was determined and found to consist of a 4,734 base pair open reading frame encoding a protein with a deduced molecular weight of ca. 174,000. gtfG was similar to other sequenced gtfs with a conserved signal sequence followed by a ca. 600-bp region distinctive for gtfG, a conserved region encoding a putative catalytic active site and a series of six direct repeats in the carboxyl terminal region implicated in glucan binding. Although comparison of gtfG to other gtfs did not show a basis for the primer-independence of the encoded enzyme or the nature of the glucan products, the gtfG sequence data provide an important basis for further studies of these enzymes.
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Affiliation(s)
- M M Vickerman
- Department of Microbiology and Immunology, School of Medicine, University of Michigan, Ann Arbor 48109-0620, USA.
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17
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Vickerman MM, Sulavik MC, Minick PE, Clewell DB. Changes in the carboxyl-terminal repeat region affect extracellular activity and glucan products of Streptococcus gordonii glucosyltransferase. Infect Immun 1996; 64:5117-28. [PMID: 8945555 PMCID: PMC174497 DOI: 10.1128/iai.64.12.5117-5128.1996] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Glucans produced by the glucosyltransferase (GTF) of Streptococcus gordonii confer a hard, cohesive phenotype (Spp+) on colonies grown on sucrose agar plates. S. gordonii strains with specific mutations in the region of gtfG that encodes the GTF carboxyl terminus were characterized. In the parental strain Challis CH1, this region included a series of six direct repeats thought to function in glucan binding. The spontaneous mutant strain CH107 had a 585-bp deletion resulting in the loss of three internal direct repeats. Insertional mutagenesis was used to construct strain CH2RPE, which had the parental repeat region but was missing 14 carboxyl-terminal amino acids. The similarly constructed strain CH4RPE had an in-frame addition of 390 nucleotides encoding two additional direct repeats. Although strains CH1, CH2RPE, and CH4RPE all had similar levels of extracellular GTF activity, strain CH107 had less than 15% of the parental activity; however, Western blots (immunoblots) indicated that the amounts of extracellular GTF protein in all four strains were similar. 13C NMR analyses indicated that partially purified GTFs from the Spp+ strains CH1, CH2RPE, and CH4RPE all produced glucans with similar ratios of alpha1,6 and alpha1,3 glucosidic linkages, whereas the Spp- strain CH107 GTF produced primarily alpha1,6-linked glucans. Transformation of strain CH107 with pAMS57, which carries the gtfG positive regulatory determinant, rgg, increased the amount of GTF activity and GTF antibody-reactive protein ca. fivefold but did not confer a hard colony phenotype on sucrose agar plates, suggesting that the type of glucan product affects the sucrose-promoted colony phenotype.
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Affiliation(s)
- M M Vickerman
- Department of Microbiology and Immunology, School of Medicine, University of Michigan, Ann Arbor 48109, USA.
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18
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Sulavik MC, Clewell DB. Rgg is a positive transcriptional regulator of the Streptococcus gordonii gtfG gene. J Bacteriol 1996; 178:5826-30. [PMID: 8824637 PMCID: PMC178431 DOI: 10.1128/jb.178.19.5826-5830.1996] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
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.
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Affiliation(s)
- M C Sulavik
- Department of Microbiology and Immunology, School of Medicine, University of Michigan, Ann Arbor 48109, USA
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19
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Newman F, Beeley JA, MacFarlane TW. Adherence of oral microorganisms to human parotid salivary proteins. Electrophoresis 1996; 17:266-70. [PMID: 8907552 DOI: 10.1002/elps.1150170146] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Bacterial colonisation of oral surfaces by microorganisms may be dependent on their interaction with specific host receptor molecules. Primary oral colonisers are known to remove specific proteins from parotid saliva. The aim of this study was to determine whether these interactions facilitate microbial attachment to a surface and hence identify specific salivary components as putative host receptor molecules. Parotid saliva was resolved by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and then electroblotted onto nitrocellulose membranes. Suspensions of fluorescently labelled microorganisms were incubated with the blots and salivary components with adherent bacteria identified as fluorescent bands under ultraviolet (UV) transillumination. Species of streptococci known to be early colonisers of the clean tooth surface were found to adhere specifically to certain salivary proteins, especially to basic proline-rich proteins (PRPs). Polymorphic variations in these patterns could form the basis of differences in oral microflora, susceptibility to oral infections and consequent disease.
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Affiliation(s)
- F Newman
- Department of Oral Sciences, University of Glasgow, UK
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20
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Jones GW, Clewell DB, Charles LG, Vickerman MM. Multiple phase variation in haemolytic, adhesive and antigenic properties of Streptococcus gordonii. MICROBIOLOGY (READING, ENGLAND) 1996; 142 ( Pt 1):181-189. [PMID: 8581164 DOI: 10.1099/13500872-142-1-181] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
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 between these phenotypes. There was evidence also of independent phase variation in adhesion to saliva-coated hydroxyapatite (Asp for adhesion to salivary pellicles), in lactose-sensitive coaggregation (Cls for coaggregation, lactose-sensitive) and in the concentrations of particular cell surface antigens (Cap for cell antigen profile) in strains that had undergone phase changes in Spp and/or Bhp. Phase variation in all these phenotypes were transitions between high and low levels of activity and each appeared to occur as an independent event. Significant associations (P << 0.0001 by contingency table analysis) between particular phenotypes such as Bhp and Asp and between Asp, Cls and Cap phenotypes, however, were apparent. The results suggest that S. gordonii cells become predisposed to phase variation and that the resulting independent phenotypic changes may give rise to phenotypically diverse streptococcal populations able to accommodate rapid and transient environmental changes in the mouth.
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Affiliation(s)
- G W Jones
- Department of Microbiology and Immunology, The Medical School
| | - D B Clewell
- Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, Ml 48109, USA
- Department of Microbiology and Immunology, The Medical School
| | - L G Charles
- Department of Microbiology and Immunology, The Medical School
| | - M M Vickerman
- Department of Microbiology and Immunology, The Medical School
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21
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Vickerman MM, Sulavik MC, Clewell DB. Oral streptococci with genetic determinants similar to the glucosyltransferase regulatory gene, rgg. Infect Immun 1995; 63:4524-7. [PMID: 7591096 PMCID: PMC173645 DOI: 10.1128/iai.63.11.4524-4527.1995] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
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 Streptococcus salivarius.
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Affiliation(s)
- M M Vickerman
- Department of Microbiology and Immunology, School of Medicine, University of Michigan, Ann Arbor 48109, USA
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22
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Vickerman MM, Jones GW. Sucrose-dependent accumulation of oral streptococci and their adhesion-defective mutants on saliva-coated hydroxyapatite. ORAL MICROBIOLOGY AND IMMUNOLOGY 1995; 10:175-82. [PMID: 7567067 DOI: 10.1111/j.1399-302x.1995.tb00139.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
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 in dental plaque. Growing cells of each strain were also examined for their ability to accumulate on saliva-coated hydroxyapatite. The addition of sucrose to the medium promoted the accumulation of strain G9B more than it promoted the accumulation of strains FC1 and C5. Sucrose also enhanced the accumulation of adhesion-defective mutants of each strain to levels similar to those of the respective parent strains. These results suggest that sucrose-dependent accumulation may facilitate the colonization of the tooth surface by these species of oral streptococci when adhesion is limited by reduced bacterial adhesiveness or limited pellicle-binding sites.
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Affiliation(s)
- M M Vickerman
- Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor 48109-0402, USA
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23
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Abstract
Bacteria in biofilms are known to be more resistant than bacteria in batch cultures to antimicrobial agents. The purpose of the present study was to develop a flow method for formation of oral biofilms permitting susceptibility testing of plaque bacteria. A brain heart infusion (BHI) Streptococcus sanguis 804 culture was pumped through a modified Robbins Device (MRD) with 25 exchangeable silicone disks at 40 ml/h. After 24-48 h disks were removed and biofilm cells dispersed by vortex mixing and low-output ultrasonication. Colony forming units (cfu)/cm2 were determined after aerobic incubation on blood agar plates. Optimal biofilm formation was found after growth for 48 h at 37 degrees C in BHI + 1% sucrose, using saliva-coated silicone disks in inverted MRDs, yielding on average 4.4 x 10(5) cfu/cm2. Similar results were obtained for S. sanguis ATCC 10556 and five clinical isolates. Testing the susceptibility of S. sanguis to chlorhexidine gluconate showed increased resistance of biofilms compared to batch culture. Thus an appropriate biofilm model for susceptibility testing of oral microorganisms has been established.
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Affiliation(s)
- T Larsen
- Department of Oral Microbiology, School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Denmark
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24
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Vacca-Smith AM, Jones CA, Levine MJ, Stinson MW. Glucosyltransferase mediates adhesion of Streptococcus gordonii to human endothelial cells in vitro. Infect Immun 1994; 62:2187-94. [PMID: 8188339 PMCID: PMC186496 DOI: 10.1128/iai.62.6.2187-2194.1994] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
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-molecular-weight dextran and heparin but not by sucrose, fibronectin, or laminin. Adhesion was also prevented by pretreatment of HUVEC with proteins dissociated from the surface of S. gordonii with 10 mM EDTA or isolated from spent culture medium. Western blot (immunoblot) assays detected a single adhesion protein of 153 kDa (AP153) on HUVEC after incubation with unfractionated extracts of streptococci. The adhesin exhibited glucosyltransferase (GTF) activity when incubated with sucrose and Triton X-100 after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The AP153 was purified by affinity chromatography on dextran beads and show to have binding activity for HUVEC, GTF activity, an amino acid composition similar to that reported for GTF of S. gordonii, and the ability to inhibit S. gordonii adhesion. Incubation of the streptococci with antibodies to the adhesin inhibited bacterial attachment to HUVEC monolayers. These results indicate that surface-localized GTF mediates adhesion of S. gordonii to HUVEC in vitro and may serve as a mechanism for colonization of the endocardium in infective endocarditis.
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Affiliation(s)
- A M Vacca-Smith
- Department of Microbiology, School of Medicine and Biomedical Sciences, State University of New York at Buffalo 14214-3005
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25
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Newman F, Beeley JA, MacFarlane TW, Galbraith J, Buchanan L. Salivary protein interactions with oral bacteria: an electrophoretic study. Electrophoresis 1993; 14:1322-7. [PMID: 8137797 DOI: 10.1002/elps.11501401203] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The relatively low levels of human salivary proteins in whole saliva as compared to the ductal secretions may be related to their interaction with oral bacteria. These interactions are thought to play an important role in the microbial colonisation of the mouth, and salivary proteins adsorbed to oral surfaces have been implicated in adherence. In this study we attempted to investigate the prevalence of interactive strains by screening a range of oral bacteria. Parotid saliva was incubated with bacterial suspensions and consequent alterations to the salivary protein profile determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). A number of salivary components were found to be preferentially removed, particularly by those species known to be primary colonizers of clean tooth surfaces.
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Affiliation(s)
- F Newman
- Department of Oral Sciences, University of Glasgow, Scotland
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26
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Jenkinson HF, Terry SD, McNab R, Tannock GW. Inactivation of the gene encoding surface protein SspA in Streptococcus gordonii DL1 affects cell interactions with human salivary agglutinin and oral actinomyces. Infect Immun 1993; 61:3199-208. [PMID: 8335350 PMCID: PMC280988 DOI: 10.1128/iai.61.8.3199-3208.1993] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
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 recombination of the erythromycin resistance (Emr) determinant ermAM onto the streptococcal chromosome. The SspA polypeptide (apparent molecular mass, 210 kDa) was detected on Western blots (immunoblots) of spheroplast extracts and extracellular culture medium proteins from wild-type strain DL1 but was absent from Emr mutants. One SspA- mutant (designated OB220) was not altered in rate or extent of aggregation by whole saliva or parotid saliva but showed reduced aggregation in the presence of purified salivary agglutinin. Mutant bacteria were unaffected in their ability to adhere to hydroxylapatite beads coated with whole or parotid saliva and were unaltered in cell surface hydrophobicity. However, the SspA- strain OB220 was deficient in binding salivary agglutinin and in binding to six strains of Actinomyces naeslundii. Therefore, expression of SspA polypeptide in S. gordonii is associated with both agglutinin-dependent and agglutinin-independent aggregation and adherence reactions of streptococcal cells.
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Affiliation(s)
- H F Jenkinson
- Department of Oral Biology and Oral Pathology, University of Otago, Dunedin, New Zealand
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27
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Kuramitsu HK. Virulence factors of mutans streptococci: role of molecular genetics. CRITICAL REVIEWS IN ORAL BIOLOGY AND MEDICINE : AN OFFICIAL PUBLICATION OF THE AMERICAN ASSOCIATION OF ORAL BIOLOGISTS 1993; 4:159-76. [PMID: 8435464 DOI: 10.1177/10454411930040020201] [Citation(s) in RCA: 268] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Biochemical approaches were utilized initially to identify the virulence factors of the mutans streptococci (primarily Streptococcus mutans and S. sobrinu). Traditional mutant analysis of these organisms further suggested the important role of several of these factors in cariogenicity. However, because these mutations were not clearly defined, the utilization of cloned genes was necessary to verify their significance. The introduction of molecular genetic approaches for characterizing these factors has led not only to a clearer understanding of the role of these virulence factors in cariogenicity but has also suggested some novel approaches for reducing further the incidence of dental caries.
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Affiliation(s)
- H K Kuramitsu
- Department of Pediatric Dentistry and Microbiology, University of Texas Health Science Center, San Antonio
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28
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Vickerman MM, Jones GW. Adhesion of glucosyltransferase phase variants to Streptococcus gordonii bacterium-glucan substrata may involve lipoteichoic acid. Infect Immun 1992; 60:4301-8. [PMID: 1398940 PMCID: PMC257466 DOI: 10.1128/iai.60.10.4301-4308.1992] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
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 in adhesiveness, adhesion between washed, [3H]thymidine-labeled cells and preformed BPM substrata was measured. Unexpectedly, the results showed that cells of both phenotypes, as well as GTF-negative cells, attached equally well to preformed BPMs, indicating that attachment to BPMs was independent of cell surface GTF activity. Initial characterization of this binding interaction suggested that a protease-sensitive component on the washed cells may be binding to lipoteichoic acids sequestered in the BPM, since exogenous lipoteichoic acid inhibited adhesion. Surprisingly, the adhesion of both Spp+ and Spp- cells was markedly inhibited in the presence of sucrose, which also released lipoteichoic acid from the BPM. These in vitro findings suggest that, in vivo, sucrose and lipoteichoic acid may modify dental plaque development by enhancing or inhibiting the attachment of additional bacteria.
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Affiliation(s)
- M M Vickerman
- Department of Cariology and General Dentistry, School of Dentistry, University of Michigan, Ann Arbor 48109
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29
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Hiroi T, Fukushima K, Kantake I, Namiki Y, Ikeda T. De novo glucan synthesis by mutans streptococcal glucosyltransferases present in pellicle promotes firm binding ofStreptococcus gordoniito tooth surfaces. FEMS Microbiol Lett 1992. [DOI: 10.1111/j.1574-6968.1992.tb05415.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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30
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Sulavik MC, Tardif G, Clewell DB. Identification of a gene, rgg, which regulates expression of glucosyltransferase and influences the Spp phenotype of Streptococcus gordonii Challis. J Bacteriol 1992; 174:3577-86. [PMID: 1534326 PMCID: PMC206044 DOI: 10.1128/jb.174.11.3577-3586.1992] [Citation(s) in RCA: 83] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
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 exhibited the same functional properties as pAM5010. Nucleotide sequence analysis of this region revealed a gene approximately 1 kb in size. The gene was designated rgg. Disruption of the chromosomal rgg gene open reading frame in an Spp+ strain resulted in strain DS512, which displayed an Spp(-)-like phenotype and had 3% of wild-type GTF activity. A plasmid containing the rgg gene was able to complement the DS512 phenotype and significantly increase GTF expression above wild-type levels. Sequence analysis and other data showed that the S. gordonii GTF determinant, designated gtfG, is located 66 bp downstream of the rgg gene. The sequence also revealed interesting inverted repeats which may play a role in the regulation of gtfG. We conclude that rgg positively regulates the expression of GTF and influences expression of the Spp phenotype.
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Affiliation(s)
- M C Sulavik
- Department of Microbiology and Immunology, School of Medicine, University of Michigan, Ann Arbor 48109-0402
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31
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Vickerman MM, Clewell DB, Jones GW. Ecological implications of glucosyltransferase phase variation in Streptococcus gordonii. Appl Environ Microbiol 1991; 57:3648-51. [PMID: 1838470 PMCID: PMC184028 DOI: 10.1128/aem.57.12.3648-3651.1991] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
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. gordonii cells throughout the oral cavity.
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Affiliation(s)
- M M Vickerman
- Department of Cariology and General Dentistry, School of Dentistry, Unviersity of Michigan, Ann Arbor 48109-0620
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