The Role of Glucan‐Binding Proteins in the Cariogenicity of <i>Streptococcus mutans</i>

Matsumura, M.; Izumi, Tohru; Matsumoto, Michi; Tsuji, Michiko; Fujiwara, Taku; Ooshima, Takashi

doi:10.1111/j.1348-0421.2003.tb03389.x

Cited by 49 publications

(50 citation statements)

References 18 publications

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“…2D) having undergone several recombinations, as identified by vector deletions (data not shown), although the intact Erm r was always retained. In contrast, deletion of a nonessential gene, e.g., gbpA, was successfully inactivated by allelic replacement in strain UA130 (12), and gbpA and gbpC were inactivated by Campbell-like insertion without duplication in S. mutans strain MT8148 (20). Merodiploid formation is indicative of a cellular response to prevent the inactivation of an essential function and occurred, for example, in Bacillus subtilis after a double crossover recombination that would have deleted the essential ilvA gene (28).…”

Section: Discussionmentioning

confidence: 99%

Functional Analysis of Glucan Binding Protein B from Streptococcus mutans

Mattos-Graner¹,

Porter²,

Smith³

et al. 2006

J Bacteriol

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Mutans streptococci are major etiological agents of dental caries, and several of their secreted products contribute to bacterial accumulation on teeth. Of these, Streptococcus mutans glucan binding protein B (GbpB) is a novel, immunologically dominant protein. Its biological function is unclear, although GbpB shares homology with a putative peptidoglycan hydrolase from S. agalactiae and S. pneumoniae, indicative of a role in murein biosynthesis. To determine the cellular function of GbpB, we used several approaches to inactivate the gene, analyze its expression, and identify interacting proteins. None of the transformants analyzed were true gbpB mutants, since they all contained both disrupted and wild-type gene copies, and expression of functional GbpB was always conserved. Thus, the inability to obtain viable gbpB null mutants supports the notion that gbpB is an essential gene. Northern blot and real-time PCR analyses suggested that induction of gbpB expression in response to stress was a strain-dependent phenomenon. Proteins that interacted with GbpB were identified in pull-down and coimmunoprecipitation assays, and these data suggest that GbpB interacts with ribosomal protein L7/L12, possibly as part of a protein complex involved in peptidoglycan synthesis and cell division.

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Section: Discussionmentioning

confidence: 99%

Functional Analysis of Glucan Binding Protein B from Streptococcus mutans

Mattos-Graner¹,

Porter²,

Smith³

et al. 2006

J Bacteriol

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“…The genes encoding these proteins are not clustered in an operon but are distributed along the S. mutans chromosome (1). GbpC is believed to be the most important Gbp since it directly contributes to the cariogenicity of S. mutans (28,33). Moreover, S. mutans strains expressing low levels of GbpC are more virulent for bacteremia, possibly due to their lower susceptibility to phagocytosis by polymorphonuclear leukocytes (34).…”

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confidence: 99%

“…Moreover, S. mutans strains expressing low levels of GbpC are more virulent for bacteremia, possibly due to their lower susceptibility to phagocytosis by polymorphonuclear leukocytes (34). Strains defective in gbpC expression exhibit a drastic reduction in sucrose-dependent adherence to glass surfaces, as well as sucrose-independent adherence to saliva-coated hydroxyapatites (28). GbpC-defective S. mutans strains also show significant deficiency in biofilm formation, as the structure of the biofilm formed is markedly different than that of the wild-type strain (24).…”

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Regulation of gbpC Expression in Streptococcus mutans

2007

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Streptococcus mutans, the principal causative agent of dental caries, produces four glucan-binding proteins (Gbp) that play major roles in bacterial adherence and pathogenesis. One of these proteins, GbpC, is an important cell surface protein involved in biofilm formation. GbpC is also important for cariogenesis, bacteremia, and infective endocarditis. In this study, we examined the regulation of gbpC expression in S. mutans strain UA159. We found that gbpC expression attains the maximum level at mid-exponential growth phase, and the half-life of the transcript is less than 2 min. Expression from PgbpC was measured using a PgbpC-gusA transcriptional fusion reporter and was analyzed under various stress conditions, including thermal, osmotic, and acid stresses. Expression of gbpC is induced under conditions of thermal stress but is repressed during growth at low pH, whereas osmotic stress had no effect on expression from PgbpC. The results from the expression analyses were further confirmed using semiquantitative reverse transcription-PCR analysis. Our results also reveal that CovR, a global response regulator in many Streptococcus spp., represses gbpC expression at the transcriptional level. We demonstrated that purified CovR protein binds directly to the promoter region of PgbpC to repress gbpC expression. Using a DNase I protection assay, we showed that CovR binds to DNA sequences surrounding PgbpC from bases ؊68 to 28 (where base 1 is the start of transcription). In summary, our results indicate that various stress conditions modulate the expression of gbpC and that CovR negatively regulates the expression of the gbpC gene by directly binding to the promoter region.

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“…Sugar starvation has been shown to induce stationary-phase survival in batch cultures of gram-positive bacteria such as Mycobacterium smegmatis, Staphylococcus aureus, Lactococcus lactis, Enterococcus faecalis, and Streptococcus pyogenes (4,6,9,29,30,36,40). S. mutans is naturally a biofilm-forming bacterium (2), and we have characterized its survival in biofilms as well as in batch cultures.A large amount of work has been done to identify genes that are required for the proper formation of biofilms by S. mutans (1,7,8,13,16,20,22,25,41,42,43). However, little is known about the survival of S. mutans within mature biofilms.…”

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Persistence of Streptococcus mutans in Stationary-Phase Batch Cultures and Biofilms

Renye

Piggot

Daneo-Moore

et al. 2004

Appl Environ Microbiol

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Streptococcus mutans is a member of oral plaque biofilms and is considered the major etiological agent of dental caries. We have characterized the survival of S. mutans strain UA159 in both batch cultures and biofilms. Bacteria grown in batch cultures in a chemically defined medium, FMC, containing an excess of glucose or sucrose caused the pH to decrease to 4.0 at the entry into stationary phase, and they survived for about 3 days. Survival was extended up to 11 days when the medium contained a limiting concentration of glucose or sucrose that was depleted by the time the bacteria reached stationary phase. Sugar-limited cultures maintained a pH of 7.0 throughout stationary phase. Their survival was shortened to 3 days by the addition of exogenous lactic acid at the entry into stationary phase. Sugar starvation did not lead to comparable survival in biofilms. Although the pH remained at 7.0, bacteria could no longer be cultured from biofilms 4 days after the imposition of glucose or sucrose starvation; BacLight staining results did not agree with survival results based on culturability. In both batch cultures and biofilms, survival could be extended by the addition of 0.5% mucin to the medium. Batch survival increased to an average of 26 (؎8) days, and an average of 2.7 ؋ 10 5 CFU per chamber were still present in biofilms that were starved of sucrose for 12 days.Streptococcus mutans is normally found within the oral cavity as a member of the dental plaque community. Even though dental plaque consists of numerous bacterial species, only the presence of S. mutans has been consistently linked with the production of dental caries (18). Within the oral cavity, S. mutans is exposed to feast or famine conditions with regard to dietary sugars. The presence of excess sugar allows for bacterial growth and the production of lactic acid. Subsequently, between sugar pulses, S. mutans may persist in a sugar-starved environment. Sugar starvation has been shown to induce stationary-phase survival in batch cultures of gram-positive bacteria such as Mycobacterium smegmatis, Staphylococcus aureus, Lactococcus lactis, Enterococcus faecalis, and Streptococcus pyogenes (4,6,9,29,30,36,40). S. mutans is naturally a biofilm-forming bacterium (2), and we have characterized its survival in biofilms as well as in batch cultures.A large amount of work has been done to identify genes that are required for the proper formation of biofilms by S. mutans (1,7,8,13,16,20,22,25,41,42,43). However, little is known about the survival of S. mutans within mature biofilms. Studies of the survival of S. mutans have focused primarily on its response to periods of acid shock. It has been shown that S. mutans grown in both batch cultures and biofilms can develop an acid tolerance response when exposed to a sublethal decrease in pH to 5.5 (14, 21, 32). Carbon starvation has been shown to enhance the acid tolerance of bacteria grown in both batch cultures and biofilms (31,33,45), but the survival of carbon-starved S. mutans, independent of an acid shock, h...

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The Role of Glucan‐Binding Proteins in the Cariogenicity of Streptococcus mutans

Cited by 49 publications

References 18 publications

Functional Analysis of Glucan Binding Protein B from Streptococcus mutans

Functional Analysis of Glucan Binding Protein B from Streptococcus mutans

Regulation of gbpC Expression in Streptococcus mutans

Persistence of Streptococcus mutans in Stationary-Phase Batch Cultures and Biofilms

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