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Team:Chiba/Project
From 2013.igem.org
introduction
Magnetic force is widely used in our life.
When we listen to the music, we use an earphone or a speaker which uses magnet. When we buy things, we use credit cards that is magnetized.
When we watch movies in our house, we use DVD which is magnetized.
Like this example, magnetic force is used everywhere.
With a Magnetic force, we can easily separate things.
In combination with quorum sensing, we can apply Magnetic force to a switch.
So our team makes E.coli magnetized.
There is so many good points to use Magnetic force
1. You don’t have to remove inducer from the reaction system (In the first place you don’t need an inducer)
2. Magnetic force has a transparency (light doesn’t)
3. It reacts immediately
overview
Some metal oxides of the spinel type i.e. Fe3O4 have ferrimagnetism because of the disparity of magnetic moment. If E.coli has it, it will be attracted by magnets.
Ordinary, Fe inside cytosol are reduced and exists as divalent ferrous ion. Fe ions, which injure the DNAs with hydroxyl radical from Fenton reaction, are isolated from cytosol by ferritin. Ferritin accumulates ferrous ions inside and oxidizes to ferric ions for prevention of Fenton reaction.
Fur controls E.coli iron metabolism. In the case of iron oversupply, fur combine with ferrous ion and restricts the expression of Fec(iron importer) and induces the expression of ferritin. In the other hand, fieF is iron efflux pump which fur doesn’t control. These maintain iron homeostasis of E.coli.
In our project, (1) we knock out genes, trxB and gor to shift the oxidation state to more oxidized state inside cytosol so that ferrous ions are easier to be oxidized and exist in cytosol. And, (2) human ferritins are overexpressed in order to deal with ferrous ions quickly which haven’t be oxidized yet. It will improve iron tolerance of E.coli. (3)We knock down fur and fieF by CRISPRi for the sake of increase the amount of iron uptake.
We have three steps to create magnetic E.coli.
- increase iron uptake
- improve iron storage
- change the iron redox state
And, there are each analytical methods.
