Tartar Research Today is a free monthly online journal that collates and summarizes the latest research about Tartar, including details on teeth, plaque, enamel, dental calculus, oral hygiene.

Two Intramolecular Isopeptide Bonds are Identified in the Crystal Structure of the Streptococcus gordonii SspB C-terminal Domain.

Forsgren N, Lamont RJ, Persson K

Department of Odontology, Umeå University, Umeå, SE-901 87, Sweden.

Streptococcus gordonii is a primary colonizer and is involved in the formation of dental plaque. This bacterium expresses several surface proteins. One of them is the adhesin SspB, which is a member of the Antigen I/II family of proteins. SspB is a large multi-domain protein that has interactions with surface molecules on other bacteria and on host cells, and is thus a key factor in the formation of biofilms. Here, we report the crystal structure of a truncated form of the SspB C-terminal domain, solved by single-wavelength anomalous dispersion to 1.5 A resolution. The structure represents the first of a C-terminal domain from a streptococcal Antigen I/II protein and is comprised of two structurally related beta-sandwich domains, C2 and C3, both with a Ca(2+) bound in equivalent positions. In each of the domains, a covalent isopeptide bond is observed between a lysine and an asparagine, a feature that is believed to be a common stabilization mechanism in Gram-positive surface proteins. S. gordonii biofilms contain attachment sites for the periodontal pathogen Porphyromonas gingivalis and the SspB C-terminal domain has been shown to have one such recognition motif, the SspB adherence region. The motif protrudes from the protein, and serves as a handle for attachment. The structure suggests several additional putative binding surfaces, and other binding clefts may be created when the full-length protein is folded.

Published 15 March 2010 in J Mol Biol, 397(3): 740-751.
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Articles on Tartar published 12 March 2010:

The effect of sucrose on plaque and saliva urease levels in vivo.   Arch Oral Biol, 55(3): 249-254.

OBJECTIVE: Dietary sugar exposures induce an immediate drop of the plaque pH. Based on in vitro observations, it was hypothesized that oral bacteria may rapidly respond to this environmental change by increasing the activity or expression of alkali-generating pathways, such as the urease pathway. The objective of this exploratory in vivo study was to determine the short-term effect of a brief sucrose exposure on plaque and saliva urease activity and expression, and to relate this effect to ... [Abstract] [Full-text]

Prevalence and distribution of serotype-specific genotypes of Aggregatibacter actinomycetemcomitans in chronic periodontitis Brazilian subjects.   Arch Oral Biol, 55(3): 242-248.

OBJECTIVE: Previous studies have suggested that Aggregatibacter actinomycetemcomitans is involved in the aetiology of aggressive periodontitis as well as chronic periodontitis. In addition, some authors have also reported that serotype-specific antigens of A. actinomycetemcomitans determine the severity of disease. This study aimed to elucidate the prevalence of A. actinomycetemcomitans and the distribution of A. actinomycetemcomitans serotypes in Brazilian subjects with chronic periodontitis. ... [Abstract] [Full-text]

Antibacterial activity of dental composites containing zinc oxide nanoparticles.   J Biomed Mater Res B Appl Biomater.

The resin-based dental composites commonly used in restorations result in more plaque accumulation than other materials. Bacterial biofilm growth contributes to secondary caries and failure of resin-based dental composites. Methods to inhibit biofilm growth on dental composites have been sought for several decades. It is demonstrated here that zinc oxide nanoparticles (ZnO-NPs) blended at 10% (w/w) fraction into dental composites display antimicrobial activity and reduce growth of bacterial ... [Abstract] [Full-text]

Articles on Tartar published 9 March 2010:

Acid tolerance mechanisms utilized by Streptococcus mutans.   Future Microbiol, 5: 403-17.

Since its discovery in 1924 by J Clarke, Streptococcus mutans has been the focus of rigorous research efforts due to its involvement in caries initiation and progression. Its ability to ferment a range of dietary carbohydrates can rapidly drop the external environmental pH, thereby making dental plaque inhabitable to many competing species and can ultimately lead to tooth decay. Acid production by this oral pathogen would prove suicidal if not for its remarkable ability to withstand the acid ... [Abstract] [Full-text]

Articles on Tartar published 4 March 2010:

Treponema denticola biofilm-induced expression of a bacteriophage, toxin-antitoxin systems and transposases.   Microbiology, 156: 774-88.

Treponema denticola is an oral spirochaete that has been strongly associated with chronic periodontitis. The bacterium exists as part of a dense biofilm (subgingival dental plaque) accreted to the tooth. To determine T. denticola gene products important for persistence as a biofilm we developed a continuous-culture biofilm model and conducted a genome-wide transcriptomic analysis of biofilm and planktonic cells. A total of 126 genes were differentially expressed with a fold change of 1.5 or ... [Abstract] [Full-text]

Effects of a mouthwash with chlorine dioxide on oral malodor and salivary bacteria: a randomized placebo-controlled 7-day trial.   Trials, 11: 14.

BACKGROUND: Previous research has shown the oxidizing properties and microbiological efficacies of chlorine dioxide (ClO2). Its clinical efficacies on oral malodor have been evaluated and reported only in short duration trials, moreover, no clinical studies have investigated its microbiological efficacies on periodontal and malodorous bacteria. Thus, the aim of this study was to assess the inhibitory effects of a mouthwash containing ClO2 used for 7 days on morning oral malodor and on salivary ... [Abstract] [Full-text]

Articles on Tartar published 3 March 2010:

Kinetics of monofluorophosphate hydrolysis in a bacterial test plaque in situ.   Caries Res, 44(1): 55-9.

Models to evaluate the anticaries potential of fluoride (F) formulations containing monofluorophosphate (MFP) should consider the release of F ion to the oral environment by its enzymatic hydrolysis. This was tested in situ, using a test plaque of a strain of Streptococcus mutans which presents high MFPase activity at pH 5.0. The test plaque was exposed to non-F or MFP (1,450 microg F/g) dentifrices and the fluid phase of the plaque was analyzed after 15, 30, 45 and 75 min. MFP concentration in ... [Abstract] [Full-text]

Articles on Tartar published 26 February 2010:

No Calcium-Fluoride-Like Deposits Detected in Plaque Shortly after a Sodium Fluoride Mouthrinse.   Caries Res, 44(2): 108-115.

Plaque 'calcium-fluoride-like' (CaF(2)-like) and fluoride deposits held by biological/bacterial calcium fluoride (Ca-F) bonds appear to be the source of cariostatic concentrations of fluoride in plaque fluid. The aim of this study was to quantify the amounts of plaque fluoride held in these reservoirs after a sodium fluoride rinse. 30 and 60 min after a 228 mug/g fluoride rinse, plaque samples were collected from 11 volunteers. Each sample was homogenized, split into 2 aliquots (aliquots 1 and ... [Abstract] [Full-text]

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