E.coli has a pathway to accumulate polyphosphoric acid. The pathway can be roughlyschematized as follows(Fig.1) This pathway is sharedby many microorganisms and is thought to have strong physiological implications.
Fig.1 The pathway to accumulate polyphosphoric in E.coli.
Since our goal is to create E.coli with increasedcapacity of phosphorus accumulation, wefocused on three genes:ppk, relA and phnCDE.
ppk is a polyphosphate synthase that elongates polyphosphateby attaching a singlephosphorus from ATP to polyphosphate.
relA is a ppGpp synthase; the synthesis of ppGpp meansthe beginning of stringentreactions, which are triggered when amino acids aredeficient and cause a decrease ingrowth rate. In addition, ppGpp competitively inhibits PPX and thus inhibits the degradationof phosphoric acid.
phnCDE is a transporter of phosphoric acid. The mainfunction of_phnCDE_is to transpor torganophosphorus. Increasing the expression of phnCDE can increase the phosphoric acidconcentration in E.coli.
The first gene circuits we will be creating in thisproject can be schematized as shown in Figure 2.
Fig.2 Gene circuits for single plasmid system
We designed dual plasmid circuits as shown in Fig.3. These genes are controlled by different inducers and after coexisting with them, we will verify the dynamics of each plasmidby changing each inducer one by one.
Fig.3 Gene circuits for dual prasmid system