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Team:Groningen:Project:Detection/staphaureus
From 2014.igem.org
Detection of Staphylococcus aureus
Quorum sensing pathway in Staphylococcus aureus
The quorum sensing system in Staphylococcus aureus consist of four genes (Figure 1). These genes are controlled by a leaky inducible promoter (P2), and encode for two membrane proteins (AgrB and AgrC), one regulator protein (AgrA) and a precursor peptide (AgrD). The membrane protein AgrB cleaves the precursor peptide AgrD so the mature signaling peptide is formed. The mature signal peptide is called autoinducing peptide (AIP). After the AIP is secreted from the cell it is able to bind to the second membrane protein AgrC. After binding the AgrC phosphorylates AgrA, AgrA is then able to induce the P2 promoter which leads to increased production of the AIPs.
Figure 1:
Quorum sensing system of Staphylococcus aureus The precursor peptide, AgrD (1), is modified to AIP by the membrane protein AgrB (2) and translocated over the membrane. The AIP binds to AgrC (3) which in turn phosphorylates AgrA (4) the phosphorylated ArgA induces the P2 promoter.
How LactoAid detects S. aureus
In our LactoAid we introduced the DNA encoding for the membrane protein AgrC and the regulator protein ArgA. When Staphylococcus aureus starts to produce the AIPs, the LactoAid should be able to sense the molecules through the same system used by S. aureus. In figure 2 the designed biobrick for the detection of S. aureus is shown. Here we also show the P2 promoter which will be induced. More about the secretion system can be found at the sectretion page
Figure 2:
Overview of the desinged detection system against Staphylococcus aureus. The proteins AgrA and AgrC are present in the LActoAid. After detection of the AIPs by AgrC the AgrA will be phosphorylated and induce the P2 promoter. The details about the activated secretion system can be found at the sectretion page.
Figure 3:
Staphylococcus aureus picture adopted from center for disease control and prevention
