Difference between revisions of "Team:UCL/Dental hygiene"
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<h1> <center> <font size = "2000px" > <font color = "white" > Healthy teeth, healthy ageing </font> </font> </center> </h1> | <h1> <center> <font size = "2000px" > <font color = "white" > Healthy teeth, healthy ageing </font> </font> </center> </h1> | ||
| − | <h3> <center> <font color = "white" > Explore how we are re-designing the oral microbiome | + | <h3> <center> <font color = "white" > Explore how we are re-designing the oral microbiome <br> to prevent tooth decay </h3> |
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| − | <div class="col-md-10 col-md-offset-1 ess-template-general animate-box"><h2> <center> | + | <div class="col-md-10 col-md-offset-1 ess-template-general animate-box"><h2> <center> Biofilm formation and cariogenesis: the problem </center> </h2> |
| − | <h4> The | + | <h4> The oral cavity is inhabited by a wide range of interacting communities of metabolically and structurally organized microorganisms which synthesize an extracellular polysaccharide matrix (EPS) enabling them to adhere to the surface of the teeth and assemble in matrix-embedded biofilms. Progressing biofilm accumulation puts the bacteria under increasing metabolic stress which leads to localized metabolite and acid accumulation and a shift in the dynamic homeostasis towards acid-tolerating species such as Gram-positive Streptococcus mutans Anderson 1992). A resultant decrease in pH causes tooth demineralization and constitutes a mechanism of dental caries. </h4> |
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| − | <div class="col-md-10 col-md-offset-1 ess-template-general animate-box"><h2> <center> | + | <div class="col-md-10 col-md-offset-1 ess-template-general animate-box"><h2> <center> Our approach: a bacteriocin producing device </center> </h2> |
| − | <h4> | + | <h4>A decrease in biofilm formation caused by interference with the viability of certain bacterial species presents an approach towards limiting cariogenesis. Our team engineered a locus capable of producing and exporting a mature form of an antimicrobial peptide known as mutacin III, first identified in Streptococcus mutans UA787 isolated from a caries-active white female patient in the late 1980s . Mutacin III is effective against a wide range of Gram positive bacteria implicated in dental caries, e.g. other strains of Streptococcus mutans and Actinomyces naeslundii, while Gram-negative bacteria are resistant to inhibition . |
| + | Mutacin III is a ribosomally synthesized 22 amino acid screw-shaped lanthionine-containing peptide differing from other bacteriocins by the presence of specific post-translational modifications introduced to the propeptide (mutA) by enzymes coded in the locus (mutBCDP). These enzymes catalyze the formation of stereospecific thioether bridges, dehydration, decarboxylation of the core peptide and leader peptide cleavage so that 10 of the 22 amino acids are modified to lanthionine, methyllanthionine, 2,3-didehydroalanine, 2,3-didehydrobutyrine and possibly S-(2-aminovinyl)-D-cysteine . Mutacin III is composed of rings connected by flexible linkers (Fig. 1) which may be important in the mechanism of bacteriocidal activity . Following export, the mature peptide is believed to form transmembrane pores as monomer aggregates leading to membrane disruption and efflux of cellular components . The content of anionic phospholipids in the membrane has been suggested to be an important factor influencing initial binding – mutacin III has a net positive charge whereas Gram-positive bacteria have a high relative amount of anionic lipids . | ||
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| − | + | The biosynthetic locus was engineered by our team in a form allowing for high-yield and fine-tuned expression of mutacin III. We placed a strong T7 promoter upstream of mutA to obtain high levels of the propeptide, a repressible pTet promoter upstream of the mutBCDP co-transcription unit and an inducible araBAD promoter for the mutT gene, coding for the ATP-binding-cassette-like transporter of mutacin III. | |
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| − | + | In one investigation of the activity of mutacin-related lantibiotic gallidermin it became clear that lantibiotics more effective in preventing biofilm formation rather than in exterminating microorganisms already embedded in biofilms. To reflect this, our device could be used to transform E. coli cells and employed as an anti-cariogenic strategy in replacement therapy. Such a novel bacterial strain would demonstrate features of a successful effector strain as it would not cause disease by itself and because it could displace the host pathogenic bacteria. Importantly, there are very few existing examples of lantibiotic resistance compared with antibiotics and only one mechanism of resistance to mutacin III, known as CprRK in Clostridium difficile, has been established . | |
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Revision as of 21:24, 15 October 2016
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Healthy teeth, healthy ageing
Explore how we are re-designing the oral microbiome
to prevent tooth decay
to prevent tooth decay
Healthy heart, healthy ageing
See how we are re-designing the gut microbiome to reduce blood pressure as way of reducing the chance of age-related complications with the heart.
Biofilm formation and cariogenesis: the problem
The oral cavity is inhabited by a wide range of interacting communities of metabolically and structurally organized microorganisms which synthesize an extracellular polysaccharide matrix (EPS) enabling them to adhere to the surface of the teeth and assemble in matrix-embedded biofilms. Progressing biofilm accumulation puts the bacteria under increasing metabolic stress which leads to localized metabolite and acid accumulation and a shift in the dynamic homeostasis towards acid-tolerating species such as Gram-positive Streptococcus mutans Anderson 1992). A resultant decrease in pH causes tooth demineralization and constitutes a mechanism of dental caries.
Our approach: a bacteriocin producing device
A decrease in biofilm formation caused by interference with the viability of certain bacterial species presents an approach towards limiting cariogenesis. Our team engineered a locus capable of producing and exporting a mature form of an antimicrobial peptide known as mutacin III, first identified in Streptococcus mutans UA787 isolated from a caries-active white female patient in the late 1980s . Mutacin III is effective against a wide range of Gram positive bacteria implicated in dental caries, e.g. other strains of Streptococcus mutans and Actinomyces naeslundii, while Gram-negative bacteria are resistant to inhibition . Mutacin III is a ribosomally synthesized 22 amino acid screw-shaped lanthionine-containing peptide differing from other bacteriocins by the presence of specific post-translational modifications introduced to the propeptide (mutA) by enzymes coded in the locus (mutBCDP). These enzymes catalyze the formation of stereospecific thioether bridges, dehydration, decarboxylation of the core peptide and leader peptide cleavage so that 10 of the 22 amino acids are modified to lanthionine, methyllanthionine, 2,3-didehydroalanine, 2,3-didehydrobutyrine and possibly S-(2-aminovinyl)-D-cysteine . Mutacin III is composed of rings connected by flexible linkers (Fig. 1) which may be important in the mechanism of bacteriocidal activity . Following export, the mature peptide is believed to form transmembrane pores as monomer aggregates leading to membrane disruption and efflux of cellular components . The content of anionic phospholipids in the membrane has been suggested to be an important factor influencing initial binding – mutacin III has a net positive charge whereas Gram-positive bacteria have a high relative amount of anionic lipids . The biosynthetic locus was engineered by our team in a form allowing for high-yield and fine-tuned expression of mutacin III. We placed a strong T7 promoter upstream of mutA to obtain high levels of the propeptide, a repressible pTet promoter upstream of the mutBCDP co-transcription unit and an inducible araBAD promoter for the mutT gene, coding for the ATP-binding-cassette-like transporter of mutacin III. In one investigation of the activity of mutacin-related lantibiotic gallidermin it became clear that lantibiotics more effective in preventing biofilm formation rather than in exterminating microorganisms already embedded in biofilms. To reflect this, our device could be used to transform E. coli cells and employed as an anti-cariogenic strategy in replacement therapy. Such a novel bacterial strain would demonstrate features of a successful effector strain as it would not cause disease by itself and because it could displace the host pathogenic bacteria. Importantly, there are very few existing examples of lantibiotic resistance compared with antibiotics and only one mechanism of resistance to mutacin III, known as CprRK in Clostridium difficile, has been established .
