Difference between revisions of "Team:MIT/Description"
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<div class="h1" style="position: absolute; top: 5vw; left: 40vw;">Background</div> | <div class="h1" style="position: absolute; top: 5vw; left: 40vw;">Background</div> | ||
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As a chronic but non-lethal condition, dental caries are often overlooked as a target for modern therapeutics, and the quality of | As a chronic but non-lethal condition, dental caries are often overlooked as a target for modern therapeutics, and the quality of | ||
dental caries treatment has lagged behind that of more life-threatening diseases such as cancer. However, it is a well established | dental caries treatment has lagged behind that of more life-threatening diseases such as cancer. However, it is a well established | ||
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cuts off the bacteria's access to oxygen, thereby forcing them to revert to anaerobic respiration. Lactic acid is released as a | cuts off the bacteria's access to oxygen, thereby forcing them to revert to anaerobic respiration. Lactic acid is released as a | ||
byproduct of bacterial respiration, and leads to demineralization of the enamel and cavity formation. </div> | byproduct of bacterial respiration, and leads to demineralization of the enamel and cavity formation. </div> | ||
| − | <div class="h1" style="position: absolute; top: 59vw; left: 38vw;">Biofilm Formation</ | + | <div class="h1" style="position: absolute; top: 59vw; left: 38vw;">Biofilm Formation</p1> |
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Revision as of 21:08, 13 October 2018
Background
Biofilm Formation
In its natural, non-pathogenic state, S. mutans lives planktonically (free-floating).
The transition from the planktonic to biofilm state requires expression of virulence genes, which is coordinated via
quorum sensing: a mode of communication employed by many bacteria to coordinate gene expression
and synchronous behavior across a population or species. In the case of S. mutans, quorum sensing results in the expression of
genes coding for extracellular glucosyltransferase (GTF) enzymes. These enzymes synthesize adhesive glucans, which are used by
the bacteria to adhere both to each other and to the enamel of the tooth.
Most quorum-sensing systems involve small, diffusible peptides which are sent out as a signal by one bacteria and
received by another. The peptides are detected by a receptor on the membrane or in the cytoplasm of other bacteria, which then
initiate a signal transduction pathway that upregulates the quorum-sensing peptide, as well as other genes related to the coordinated
behavior of the population. Once enough of the signal has been received by the majority of the population, bacterial behavior
shifts to perform a synchronized activity.Biofilm formation is one of the synchronized behaviors initiated by quorum sensing.
During this process, S. Mutans create and perpetuate the Competence Stimulating Peptide (CSP), a small molecule that is used to
initiate the formation of dental plaque. The pathway through which the cells sense and respond to CSP is referred to the ComCDE pathway.
Competence Stimulating Peptide (CSP)
Small peptide communication signal produced by S. mutans in quorum sensing.
ComD
ComD: Receptor of CSP
Phosphorylation
ComD phosphorylates the response regulator
ComE
ComE: Response Regulator
Genetic Response
Response regulator binds to and activates transcription of pro-biofilm genes
(hover over each element to learn about its role)
Our goal is to port the ComCDE system into Human Embryonic Kidney (HEK) cells. This would allow our engineered cells
to sense the presence of CSP and therefore detect when biofilm formation is about to occur. ComD and ComE will be
expressed constitutively, while our three outputs (ScFv's P126 and P136, and Kappa casein) will be expressed under the ComE
promoter, which is activated by the ComE response regulator protein as described above.
Upon activation of our biofilm-sensing system, our cells will output proteins that have been shown to
reduce the biofilm-forming capabilities of S. mutans.
Our first protein is kappa casein, a protein derived from bovine milk. It interferes with the adhesive power of the
glucans post synthesis through a combination of hydrophilicity and negative charge (Vacca-Smith, 1994).
Our second option is using Single Chain Variable Fragments (ScFv's), which are comprised of the variable fragments of
monoclonal antibodies joined by a short peptide linker. Our two ScFv's, P126 and P136, bind to the N and C termini of the
glucosyltransferases, preventing the production of glucans. (Fukushima, 1992)
Quorum Sensing in S. mutans
THIS SECTION IS STILL IN PROGRESS! WAITING ON FORMAL TEXT FROM SENSING TEAM :)