Effects of Variations in pH and Hypothiocyanite Concentrations on S. mutans Glucose Metabolism

1987 ◽  
Vol 66 (2) ◽  
pp. 486-491 ◽  
Author(s):  
B. Mansson-Rahemtulla ◽  
D.C. Baldone ◽  
K.M. Pruitt ◽  
F. Rahemtulla
Keyword(s):  
Glucose Metabolism ◽  
Glucose Uptake ◽  
Streptococcus Mutans ◽  
Low Ph ◽  
Oral Streptococci ◽  
Positive Correlation ◽  
Ph Changes ◽  
Glucose Incorporation ◽  
Dependent Inhibition ◽  
Ph Dependent

Hypothiocyanous acid (HOSCN) and hypothiocyanite (OSCN-) were generated by the antibody-independent salivary peroxidase (SP) system. The metabolism of Streptococcus mutans NCTC 10449 was examined by uniformly labeled glucose incorporation studies. We found that the SP-system causes a pH-dependent inhibition of 14C-labeled glucose uptake, and that the effects of HOSCN/OSCN- are bacteriostatic. The results also showed that, at low pH, bacteria required more time to recover fully from HOSCN/OSCN- inhibition. When control experiments were performed in the absence of HOSCN/OSCN-, but the pH was varied, we found a positive correlation between pH and the rate of 14C-glucose incorporation. The results also showed that pH did not affect the maximum incorporation of 14C-glucose, demonstrating that S. mutans can adapt to pH changes in the environment. Based on the data obtained, we postulate that the antibody-independent SP system plays an important role in the regulation of the metabolism of oral streptococci.

Phosphoenolpyruvate-Dependent Glucose Transport in Oral Streptococci

1973 ◽  
Vol 52 (6) ◽  
pp. 1209-1215 ◽  
Author(s):  
Charles F. Schachtele ◽  
John A. Mayo
Keyword(s):  
Glucose Uptake ◽  
Streptococcus Mutans ◽  
Glucose Transport ◽  
Enzyme System ◽  
Cell Suspensions ◽  
Oral Streptococci ◽  
Phosphotransferase System ◽  
Resting Cell

Streptococcus mutans, S sanguis, and S salivarius use a phosphoenolpyruvate (PEP)-dependent phosphotransferase system that results in phosphorylation of glucose at carbon 6. This enzyme system is not sensitive to fluoride. Glucose uptake into resting cell suspensions is sensitive to fluoride because of inhibition of intracellular PEP production. The glucose phosphotransferase system is constitutive in oral streptococci.

scholarly journals pH-dependent inhibition by azide and fluoride of the iron superoxide dismutase from Propionibacterium shermanii

1998 ◽  
Vol 331 (2) ◽  
pp. 403-407 ◽  
Author(s):  
Beate MEIER ◽  
Christoph SCHERK ◽  
Marius SCHMIDT ◽  
Fritz PARAK
Keyword(s):  
Superoxide Dismutase ◽  
Active Site ◽  
Low Ph ◽  
Superoxide Dismutases ◽  
Iron Superoxide Dismutase ◽  
Propionibacterium Shermanii ◽  
Hydroxyl Anion ◽  
Dependent Inhibition ◽  
Ph Dependent ◽  
A Minor

The iron-containing superoxide dismutase from Propionibacterium shermanii shows, in contrast with other iron superoxide dismutases, only a minor inhibition by azide or fluoride (10–100 mM) of up to 23% at pH 7.8. The activity of the protein with Mn bound to the active site was not diminished under the same conditions. The binding constant between azide and the Fe3+ ion was determined as approx. 2 mM and for fluoride approx. 2.3 mM; they are so far comparable to those known for other iron superoxide dismutases. This seems to be a discrepancy because all other iron superoxide dismutases so far known are described as being inhibited by 50–70% by 10 mM azide. However, towards lower pH there was a drastically increased inhibition by both anions. At pH 6.8 about 80% inhibition was exhibited by azide or fluoride at a concentration of 10 mM or higher. In contrast, on increasing the pH, azide or fluoride still bound to the Fe3+ at the active site but their inhibition capacity decreased. This observation implies that both anions bind to the metal at a position that is empty at low pH, whereas at higher pH water or a negatively charged hydroxyl anion is bound. It is likely that the superoxide anion binds to the same position and has to replace the sixth ligand, leading to a diminished catalytic activity of the superoxide dismutase owing to steric and/or electrostatic inhibition of the ligand.

Stress-responsive proteins are upregulated in Streptococcus mutans during acid tolerance

Microbiology ◽  
2004 ◽  
Vol 150 (5) ◽  
pp. 1339-1351 ◽  
Author(s):  
Alice C. L. Len ◽  
Derek W. S. Harty ◽  
Nicholas A. Jacques
Keyword(s):  
Streptococcus Mutans ◽  
Elongation Factor ◽  
Acid Tolerance ◽  
Proteome Analysis ◽  
Low Ph ◽  
Lactobacillus Helveticus ◽  
Oral Streptococci ◽  
Flight Mass Spectrometry ◽  
Future Assessment ◽  
Acid Tolerant

Streptococcus mutans is an important pathogen in the initiation of dental caries as the bacterium remains metabolically active when the environment becomes acidic. The mechanisms underlying this ability to survive and proliferate at low pH remain an area of intense investigation. Differential two-dimensional electrophoretic proteome analysis of S. mutans grown at steady state in continuous culture at pH 7·0 or pH 5·0 enabled the resolution of 199 cellular and extracellular protein spots with altered levels of expression. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry identified 167 of these protein spots. Sixty-one were associated with stress-responsive pathways involved in DNA replication, transcription, translation, protein folding and proteolysis. The 61 protein spots represented isoforms or cleavage products of 30 different proteins, of which 25 were either upregulated or uniquely expressed during acid-tolerant growth at pH 5·0. Among the unique and upregulated proteins were five that have not been previously identified as being associated with acid tolerance in S. mutans and/or which have not been studied in any detail in oral streptococci. These were the single-stranded DNA-binding protein, Ssb, the transcription elongation factor, GreA, the RNA exonuclease, polyribonucleotide nucleotidyltransferase (PnpA), and two proteinases, the ATP-binding subunit, ClpL, of the Clp family of proteinases and a proteinase encoded by the pep gene family with properties similar to the dipeptidase, PepD, of Lactobacillus helveticus. The identification of these and other differentially expressed proteins associated with an acid-tolerant-growth phenotype provides new information on targets for mutagenic studies that will allow the future assessment of their physiological significance in the survival and proliferation of S. mutans in low pH environments.

scholarly journals Effects of proteins and polynucleotides on the activity of various hydrolases

1972 ◽  
Vol 127 (5) ◽  
pp. 795-800 ◽  
Author(s):  
M. J. Palmieri ◽  
O. Koldovský
Keyword(s):  
Specific Activity ◽  
Inhibitory Effect ◽  
Low Ph ◽  
Acid Hydrolases ◽  
Ileal Mucosa ◽  
Suckling Rats ◽  
Assay Mixture ◽  
Dependent Inhibition ◽  
Ph Dependent ◽  
The Relationship

The effect of various macromolecules on the activity of several hydrolases was studied. Dilution of partially purified acid β-galactosidase from ileal mucosa of suckling rats resulted in a decrease of specific activity. The relationship between specific activity and dilution of the enzyme suggests a dissociation of the enzyme. This could be prevented by addition of several proteins tested. However, addition of DNA to the assay mixture for acid β-galactosidase caused an inhibition. This inhibition could be prevented by addition of proteins. Other polynucleotides and tRNA also exert an inhibitory effect that is prevented by albumin, but nucleotides have no effect. This inhibition occurs maximally at a low pH (3.0–4.0); no inhibition is observed at pH5.5. A similar pH-dependent inhibition by DNA was also found with various other acid hydrolases.

scholarly journals The F-ATPase Operon Promoter of Streptococcus mutans Is Transcriptionally Regulated in Response to External pH

2004 ◽  
Vol 186 (24) ◽  
pp. 8524-8528 ◽  
Author(s):  
Wendi L. Kuhnert ◽  
Guolu Zheng ◽  
Roberta C. Faustoferri ◽  
Robert G. Quivey
Keyword(s):  
Streptococcus Mutans ◽  
Adaptive Response ◽  
Chloramphenicol Acetyltransferase ◽  
Low Ph ◽  
Ph Dependent ◽  
External Ph

ABSTRACT 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.

scholarly journals SUN-657 The Effect of Simvastatin on Glucose Metabolism in Primary Human Muscle Cells

2020 ◽  
Vol 4 (Supplement_1) ◽  
Author(s):  
Selina Mäkinen ◽  
Neeta Datta-Sengupta ◽  
Yen Nguyen ◽  
Petro Kyrylenko ◽  
Markku Laakso ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Glucose Metabolism ◽  
Glucose Uptake ◽  
Human Skeletal Muscle ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Acid Form ◽  
Lactone Form ◽  
Human Skeletal Muscle Cells ◽  
Glucose Incorporation

Abstract Statin use, especially treatment with simvastatin, is associated with impaired insulin secretion and whole-body insulin sensitivity, and increased risk for T2D. Here, we investigated the direct effects of lactone- and acid-forms of simvastatin on glucose metabolism in primary human skeletal muscle cells. Exposure of human myotubes to lactone-form simvastatin for 48 h increased glucose uptake and glucose incorporation into glycogen, whereas the acid-form did not affect glucose uptake and decreased glucose incorporation into glycogen. These metabolic actions were accompanied by changes in insulin signaling, as phosphorylation of AS160 and GSK3β was upregulated with lactone-, but not with acid-form simvastatin. Exposure to both lactone and acid-forms of simvastatin led to a decrease in glycolysis and glycolytic capacity, as well as to a decrease in mitochondrial respiration and ATP production. Collectively these data indicate that lactone- and acid forms of simvastatin exhibit differences such that lactone-form increases, and acid-form impairs glucose incorporation into glycogen. Exposure to either form of simvastatin, however, impairs glycolysis and mitochondrial oxidative metabolism in human skeletal muscle cells.

scholarly journals Testosterone activates glucose metabolism through AMPK and androgen signaling in cardiomyocyte hypertrophy

2021 ◽  
Vol 54 (1) ◽  
Author(s):  
Mayarling Francisca Troncoso ◽  
Mario Pavez ◽  
Carlos Wilson ◽  
Daniel Lagos ◽  
Javier Duran ◽  
...  
Keyword(s):  
Glucose Metabolism ◽  
Cardiac Hypertrophy ◽  
Glucose Uptake ◽  
Male Rats ◽  
Cardiomyocyte Hypertrophy ◽  
Mrna Levels ◽  
Elevated Glucose ◽  
Amp Activated Protein Kinase ◽  
Cultured Cardiomyocytes

Abstract Background Testosterone regulates nutrient and energy balance to maintain protein synthesis and metabolism in cardiomyocytes, but supraphysiological concentrations induce cardiac hypertrophy. Previously, we determined that testosterone increased glucose uptake—via AMP-activated protein kinase (AMPK)—after acute treatment in cardiomyocytes. However, whether elevated glucose uptake is involved in long-term changes of glucose metabolism or is required during cardiomyocyte growth remained unknown. In this study, we hypothesized that glucose uptake and glycolysis increase in testosterone-treated cardiomyocytes through AMPK and androgen receptor (AR). Methods Cultured cardiomyocytes were stimulated with 100 nM testosterone for 24 h, and hypertrophy was verified by increased cell size and mRNA levels of β-myosin heavy chain (β-mhc). Glucose uptake was assessed by 2-NBDG. Glycolysis and glycolytic capacity were determined by measuring extracellular acidification rate (ECAR). Results Testosterone induced cardiomyocyte hypertrophy that was accompanied by increased glucose uptake, glycolysis enhancement and upregulated mRNA expression of hexokinase 2. In addition, testosterone increased AMPK phosphorylation (Thr172), while inhibition of both AMPK and AR blocked glycolysis and cardiomyocyte hypertrophy induced by testosterone. Moreover, testosterone supplementation in adult male rats by 5 weeks induced cardiac hypertrophy and upregulated β-mhc, Hk2 and Pfk2 mRNA levels. Conclusion These results indicate that testosterone stimulates glucose metabolism by activation of AMPK and AR signaling which are critical to induce cardiomyocyte hypertrophy.

scholarly journals LncRNA HOTAIR regulates glucose transporter Glut1 expression and glucose uptake in macrophages during inflammation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Monira Obaid ◽  
S. M. Nashir Udden ◽  
Prasanna Alluri ◽  
Subhrangsu S. Mandal
Keyword(s):  
Immune Response ◽  
Glucose Metabolism ◽  
Glucose Uptake ◽  
Immune Cells ◽  
Glucose Transporter ◽  
Energy Needs ◽  
Glut1 Expression ◽  
Lncrna Hotair ◽  
Upstream Regulators ◽  
Glucose Transporter Glut1

AbstractInflammation plays central roles in the immune response. Inflammatory response normally requires higher energy and therefore is associated with glucose metabolism. Our recent study demonstrates that lncRNA HOTAIR plays key roles in NF-kB activation, cytokine expression, and inflammation. Here, we investigated if HOTAIR plays any role in the regulation of glucose metabolism in immune cells during inflammation. Our results demonstrate that LPS-induced inflammation induces the expression of glucose transporter isoform 1 (Glut1) which controls the glucose uptake in macrophages. LPS-induced Glut1 expression is regulated via NF-kB activation. Importantly, siRNA-mediated knockdown of HOTAIR suppressed the LPS-induced expression of Glut1 suggesting key roles of HOTAIR in LPS-induced Glut1 expression in macrophage. HOTAIR induces NF-kB activation, which in turn increases Glut1 expression in response to LPS. We also found that HOTAIR regulates glucose uptake in macrophages during LPS-induced inflammation and its knockdown decreases LPS-induced increased glucose uptake. HOTAIR also regulates other upstream regulators of glucose metabolism such as PTEN and HIF1α, suggesting its multimodal functions in glucose metabolism. Overall, our study demonstrated that lncRNA HOTAIR plays key roles in LPS-induced Glut1 expression and glucose uptake by activating NF-kB and hence HOTAIR regulates metabolic programming in immune cells potentially to meet the energy needs during the immune response.

scholarly journals Low-Dose Acrolein, an Endogenous and Exogenous Toxic Molecule, Inhibits Glucose Transport via an Inhibition of Akt-Regulated GLUT4 Signaling in Skeletal Muscle Cells

2021 ◽  
Vol 22 (13) ◽  
pp. 7228
Author(s):  
Ching-Chia Wang ◽  
Huang-Jen Chen ◽  
Ding-Cheng Chan ◽  
Chen-Yuan Chiu ◽  
Shing-Hwa Liu ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Glucose Metabolism ◽  
Glucose Tolerance ◽  
Protein Expression ◽  
Glucose Uptake ◽  
Glucose Transport ◽  
Diabetic Patients ◽  
Type 2 Diabetic Patients ◽  
Type 2 Diabetic

Urinary acrolein adduct levels have been reported to be increased in both habitual smokers and type-2 diabetic patients. The impairment of glucose transport in skeletal muscles is a major factor responsible for glucose uptake reduction in type-2 diabetic patients. The effect of acrolein on glucose metabolism in skeletal muscle remains unclear. Here, we investigated whether acrolein affects muscular glucose metabolism in vitro and glucose tolerance in vivo. Exposure of mice to acrolein (2.5 and 5 mg/kg/day) for 4 weeks substantially increased fasting blood glucose and impaired glucose tolerance. The glucose transporter-4 (GLUT4) protein expression was significantly decreased in soleus muscles of acrolein-treated mice. The glucose uptake was significantly decreased in differentiated C2C12 myotubes treated with a non-cytotoxic dose of acrolein (1 μM) for 24 and 72 h. Acrolein (0.5–2 μM) also significantly decreased the GLUT4 expression in myotubes. Acrolein suppressed the phosphorylation of glucose metabolic signals IRS1, Akt, mTOR, p70S6K, and GSK3α/β. Over-expression of constitutive activation of Akt reversed the inhibitory effects of acrolein on GLUT4 protein expression and glucose uptake in myotubes. These results suggest that acrolein at doses relevant to human exposure dysregulates glucose metabolism in skeletal muscle cells and impairs glucose tolerance in mice.

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