Nkx2.3 transcription factor is a key regulator of mucous cell identity in salivary glands.

Saliva is vital to oral health, fulfilling multiple functions in the oral cavity. Three pairs of major salivary glands and hundreds of minor salivary glands contribute to saliva production. The secretory acinar cells within these glands include two distinct populations.

Short-term and bystander effects of radiation on murine submandibular glands.

Many patients treated for head and neck cancers experience salivary gland hypofunction due to radiation damage. Understanding the mechanisms of cellular damage induced by radiation treatment is important in order to design methods of radioprotection. In addition, it is crucial to recognize the indirect effects of irradiation and the systemic responses that may alter saliva secretion.

Analysis of the Streptococcus mutans Proteome during Acid and Oxidative Stress Reveals Modules of Protein Coexpression and an Expanded Role for the TreR Transcriptional Regulator.

Streptococcus mutans promotes a tooth-damaging dysbiosis in the oral microbiota because it can form biofilms and survive acid stress better than most of its ecological competitors, which are typically health associated. Many of these commensals produce hydrogen peroxide; therefore, S. mutans must manage both oxidative stress and acid stress with coordinated and complex physiological responses.

Streptococcus mutans SpxA2 relays the signal of cell envelope stress from LiaR to effectors that maintain cell wall and membrane homeostasis.

Streptococcus mutans is a major etiologic agent of dental caries, which is the most common chronic infectious disease worldwide. S. mutans is particularly adept at causing caries due to its exceptional capacity to form biofilms and its ability to survive acidic conditions that arrest acid production and growth in many more benign members of the oral microbiota.

Disruption of l-Rhamnose Biosynthesis Results in Severe Growth Defects in Streptococcus mutans.

The rhamnose-glucose cell wall polysaccharide (RGP) of plays a significant role in cell division, virulence, and stress protection. Prior studies examined function of the RGP using strains carrying deletions in the machinery involved in RGP assembly. In this study, we explored loss of the substrate for RGP, l-rhamnose, via deletion of (encoding the protein responsible for the terminal step in l-rhamnose biosynthesis).

Streptococcus mutans requires mature rhamnose-glucose polysaccharides for proper pathophysiology, morphogenesis and cellular division.

The cell wall of Gram-positive bacteria has been shown to mediate environmental stress tolerance, antibiotic susceptibility, host immune evasion and overall virulence. The majority of these traits have been demonstrated for the well-studied system of wall teichoic acid (WTA) synthesis, a common cell wall polysaccharide among Gram-positive organisms. Streptococcus mutans, a Gram-positive odontopathogen that contributes to the enamel-destructive disease dental caries, lacks the capabilities to generate WTA.

Inactivation of genes and impairs its pathogenicity .

orchestrates the development of a biofilm that causes dental caries in the presence of dietary sucrose, and, in the bloodstream, can cause systemic infections. The development of a cariogenic biofilm is dependent on the formation of an extracellular matrix rich in exopolysaccharides, which contains extracellular DNA (eDNA) and lipoteichoic acids (LTAs). While the exopolysaccharides are virulence markers, the involvement of genes linked to eDNA and LTAs metabolism in the pathogenicity of remains unclear.

Deficiency of BrpA in Streptococcus mutans reduces virulence in rat caries model.

Our recent studies have shown that BrpA in Streptococcus mutans plays a critical role in cell envelope biogenesis, stress responses, and biofilm formation. In this study, a 10-species consortium was used to assess how BrpA deficiency influences the establishment, persistence, and competitiveness of S. mutans during growth in a community under conditions typical of the oral cavity.

Extracellular DNA and lipoteichoic acids interact with exopolysaccharides in the extracellular matrix of Streptococcus mutans biofilms.

Streptococcus mutans-derived exopolysaccharides are virulence determinants in the matrix of biofilms that cause caries. Extracellular DNA (eDNA) and lipoteichoic acid (LTA) are found in cariogenic biofilms, but their functions are unclear. Therefore, strains of S.

A Modified Chromogenic Assay for Determination of the Ratio of Free Intracellular NAD/NADH in .

Nicotinamide adenine dinucleotide is a coenzyme present in all kingdoms of life and exists in two forms: oxidized (NAD) and reduced (NADH). NAD(H) is involved in a multitude of essential metabolic redox reactions, providing oxidizing or reducing equivalents. The ratio of free intracellular NAD/NADH is fundamentally important in the maintenance of cellular redox homeostasis (Ying, 2008).

What are We Learning and What Can We Learn from the Human Oral Microbiome Project?

Extraordinary technological advances have greatly accelerated our ability to identify bacteria, at the species level, present in clinical samples taken from the human mouth. In addition, technologies are evolving such that the oral samples can be analyzed for their protein and metabolic products. As a result, pictures are the advent of personalized dental medicine is becoming closer to reality.

PlsX deletion impacts fatty acid synthesis and acid adaptation in Streptococcus mutans.

Streptococcus mutans, one of the primary causative agents of dental caries in humans, ferments dietary sugars in the mouth to produce organic acids. These acids lower local pH values, resulting in demineralization of the tooth enamel, leading to caries. To survive acidic environments, Strep.

β-Phosphoglucomutase contributes to aciduricity in Streptococcus mutans.

Streptococcus mutans encounters an array of sugar moieties within the oral cavity due to a varied human diet. One such sugar is β-d-glucose 1-phosphate (βDG1P), which must be converted to glucose 6-phosphate (G6P) before further metabolism to lactic acid. The conversion of βDG1P to G6P is mediated by β-phosphoglucomutase, which has not been previously observed in any oral streptococci, but has been extensively characterized and the gene designated pgmB in Lactococcus lactis.

The Streptococcus mutans aminotransferase encoded by ilvE is regulated by CodY and CcpA.

The aminotransferase IlvE was implicated in the acid tolerance response of Streptococcus mutans when a mutation in its gene resulted in an acid-sensitive phenotype (B. Santiago, M. MacGilvray, R.

Role of DNA base excision repair in the mutability and virulence of Streptococcus mutans.

The oral pathogen, Streptococcus mutans, possesses inducible DNA repair defences for protection against pH fluctuations and production of reactive oxygen metabolites such as hydrogen peroxide (H(2) O(2) ), which are present in the oral cavity. DNA base excision repair (BER) has a critical role in genome maintenance by preventing the accumulation of mutations associated with environmental factors and normal products of cellular metabolism. In this study, we examined the consequences of compromising the DNA glycosylases (Fpg and MutY) and endonucleases (Smx and Smn) of the BER pathway and their relative role in adaptation and virulence.

The branched-chain amino acid aminotransferase encoded by ilvE is involved in acid tolerance in Streptococcus mutans.

The ability of Streptococcus mutans to produce and tolerate organic acids from carbohydrate metabolism represents a major virulence factor responsible for the formation of carious lesions. Pyruvate is a key metabolic intermediate that, when rerouted to other metabolic pathways such as amino acid biosynthesis, results in the alleviation of acid stress by reducing acid end products and aiding in maintenance of intracellular pH. Amino acid biosynthetic genes such as ilvC and ilvE were identified as being upregulated in a proteome analysis of Streptococcus mutans under acid stress conditions (A.

Mutation of the NADH oxidase gene (nox) reveals an overlap of the oxygen- and acid-mediated stress responses in Streptococcus mutans.

NADH oxidase (Nox) is a flavin-containing enzyme used by Streptococcus mutans to reduce dissolved oxygen encountered during growth in the oral cavity. In this study, we characterized the role of the NADH oxidase in the oxidative and acid stress responses of S. mutans.

Smx nuclease is the major, low-pH-inducible apurinic/apyrimidinic endonuclease in Streptococcus mutans.

The causative agent of dental caries in humans, Streptococcus mutans, outcompetes other bacterial species in the oral cavity and causes disease by surviving acidic conditions in dental plaque. We have previously reported that the low-pH survival strategy of S. mutans includes the ability to induce a DNA repair system that appears to involve an enzyme with exonuclease functions (K.

The F-ATPase operon promoter of Streptococcus mutans is transcriptionally regulated in response to external pH.

Streptococcus mutans F-ATPase, the major component of the acid-adaptive response of the organism, is transcriptionally upregulated at low pH. Fusions of the F-ATPase promoter to chloramphenicol acetyltransferase indicated that pH-dependent expression is still observed with a short promoter that contains a domain conserved between streptococcal ATPase operons.