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Team:Evry/Project FUR
From 2013.igem.org
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| - | Iron is an essential element in the development of <i> | + | Iron is an essential element in the development of <i>E. coli</i>, but also, it can be toxic and <i>E. coli</i> can be killed, if iron is absorbed in high quantity. Using the ferric-uptake regulator protein (Fur), bacteria developed an advanced system to regulate their iron homeostasis. |
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| - | The Fur protein is a transcriptional repressor of more than 90 genes involved, in majority, in iron homeostasis (Revue + “Iron and metal regulation in bacteria”, Klaus Hantke). It plays an important role in the control of the intracellular concentration of iron in E. coli. | + | The Fur protein is a transcriptional repressor of more than 90 genes involved, in majority, in iron homeostasis (Revue + “Iron and metal regulation in bacteria”, Klaus Hantke). It plays an important role in the control of the intracellular concentration of iron in <i>E. coli</i>. |
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| - | Fur acts as a positive repressor in presence of ferrous ion ( | + | Fur acts as a positive repressor in presence of ferrous ion (Fe<sup>2+</sup>), its co-repressor. Then, Fe<sup>2+</sup> binds to the Fur protein (one ferrous ion per subunit of Fur), it will lead to a structural modification and induce the dimerization of Fur and Fe<sup>2+</sup>. Then the homodimeric Fur-Fe<sup>2+</sup> complex will bind to the DNA in a Fur Binding Site and inhibit the mRNA transcription. In absence of Fe<sup>2+</sup>, a disinhibiting effect occurs and mRNA transcription can be done. |
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Before going in the detail of our construction, we needed a iron marker in <i>E. coli</i>. Thus, we selected the FUR protein which negatively regulates the downstream genes. It is used in the iron regulation of the bacterium and smoothly shuts down the production ot siderophores, natural chelators of iron in the environment in iron depletion situation. When the concentration of iron exceeds 10<sup>6</sup>, the FUR proteins binds the ion, dimerizes and its inhibitory mechanism is activated. Below this threshold, the FUR protein's inhibition is suppressed and indirectly activates the downstream genes. | Before going in the detail of our construction, we needed a iron marker in <i>E. coli</i>. Thus, we selected the FUR protein which negatively regulates the downstream genes. It is used in the iron regulation of the bacterium and smoothly shuts down the production ot siderophores, natural chelators of iron in the environment in iron depletion situation. When the concentration of iron exceeds 10<sup>6</sup>, the FUR proteins binds the ion, dimerizes and its inhibitory mechanism is activated. Below this threshold, the FUR protein's inhibition is suppressed and indirectly activates the downstream genes. | ||
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| - | + | <div class="captionedPicture" style="width:100%;align:center;"> | |
| - | + | <a title="Meca_RyhB" href="https://static.igem.org/mediawiki/2013/4/45/Sch%C3%A9mas_1.png"> | |
| - | + | <img alt="Meca_RyhB" src="https://static.igem.org/mediawiki/2013/4/45/Sch%C3%A9mas_1.png" class="Picture"/> | |
| - | + | </a> | |
| - | + | <div class="caption"> | |
| - | + | <b>Figure 3:</b> Construction.. | |
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<div class="captionedPicture" style="width:20%;float:center;"> | <div class="captionedPicture" style="width:20%;float:center;"> | ||
| - | <a title="Enterobactines Structure" href=" | + | <a title="Enterobactines Structure" href="https://static.igem.org/mediawiki/2013/2/24/Enterobactine_structure.png"> |
| - | https://static.igem.org/mediawiki/2013/2/24/Enterobactine_structure.png"> | + | |
<img alt="Enterobactines Structure" src="https://static.igem.org/mediawiki/2013/2/24/Enterobactine_structure.png" class="Picture"/> | <img alt="Enterobactines Structure" src="https://static.igem.org/mediawiki/2013/2/24/Enterobactine_structure.png" class="Picture"/> | ||
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Revision as of 21:30, 3 October 2013
FUR system
Iron is an essential element in the development of E. coli, but also, it can be toxic and E. coli can be killed, if iron is absorbed in high quantity. Using the ferric-uptake regulator protein (Fur), bacteria developed an advanced system to regulate their iron homeostasis.
FUR protein (Ferric Uptake Regulator)
The Fur protein is a transcriptional repressor of more than 90 genes involved, in majority, in iron homeostasis (Revue + “Iron and metal regulation in bacteria”, Klaus Hantke). It plays an important role in the control of the intracellular concentration of iron in E. coli.
Fur acts as a positive repressor in presence of ferrous ion (Fe2+), its co-repressor. Then, Fe2+ binds to the Fur protein (one ferrous ion per subunit of Fur), it will lead to a structural modification and induce the dimerization of Fur and Fe2+. Then the homodimeric Fur-Fe2+ complex will bind to the DNA in a Fur Binding Site and inhibit the mRNA transcription. In absence of Fe2+, a disinhibiting effect occurs and mRNA transcription can be done.
FUR binding site architecture
Natural inverter system
Constructions
Our goal is to lower the iron absorption from the intestins to the blood by using an iron chelating bacteria, Iron Coli. The objective of the labwork is to design an iron-sensible promoter with FUR and overexpress the enterobactin synthesis pathway in the presence of iron.
Before going in the detail of our construction, we needed a iron marker in E. coli. Thus, we selected the FUR protein which negatively regulates the downstream genes. It is used in the iron regulation of the bacterium and smoothly shuts down the production ot siderophores, natural chelators of iron in the environment in iron depletion situation. When the concentration of iron exceeds 106, the FUR proteins binds the ion, dimerizes and its inhibitory mechanism is activated. Below this threshold, the FUR protein's inhibition is suppressed and indirectly activates the downstream genes.
Siderophores
