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towards attractants. The key to this system and the first link in the chain is the bacterial | towards attractants. The key to this system and the first link in the chain is the bacterial | ||
chemoreceptor - a membrane protein that binds the effector and transduces the signal down | chemoreceptor - a membrane protein that binds the effector and transduces the signal down | ||
− | the line. | + | the line.<br> |
− | Despite it's advantages this system is still rather limited, bacterial chemoreceptors have evolved | + | Despite it's advantages this system is still rather limited, bacterial chemoreceptors have evolved |
to sense specific materials that either benefit or harm the cell in some way. The specificity of | to sense specific materials that either benefit or harm the cell in some way. The specificity of | ||
a receptor is determined by its ligand binding domain. This domain is the focus of project S.Tar. | a receptor is determined by its ligand binding domain. This domain is the focus of project S.Tar. | ||
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− | <p class="text-center"><b> | + | <p class="text-center"><b>Fig. 1:</b> A bacterial sense of direction.</p> |
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Our attempts did not end here, we also present other attempts to fuse ligand binding | Our attempts did not end here, we also present other attempts to fuse ligand binding | ||
domains:<br> | domains:<br> | ||
− | -LBD from human origin in order to induce chemotaxis towards | + | - LBD from human origin in order to induce chemotaxis towards |
− | + | <a href="https://2016.igem.org/Team:Technion_Israel/Modifications/EstoTar" >Estrogen hormone</a>. | |
− | <br> | + | <br> |
− | -LBD from a different receptor of <I>E.coli</I>, <a hret="https://2016.igem.org/Team:Technion_Israel/Modifications/narx" >Narx receptor</a>, which is not part of the chemotaxis system. | + | - LBD from a different receptor of <I>E.coli</I>, |
− | <br> | + | <a hret="https://2016.igem.org/Team:Technion_Israel/Modifications/narx" >Narx receptor</a>, |
− | -A novel lock and key system which relies on | + | which is not part of the chemotaxis system. |
− | + | <br> | |
− | + | - A novel lock and key system which relies on | |
+ | <a href="https://2016.igem.org/Team:Technion_Israel/Modifications/Intein" >intein proteins</a>. The purpose of these proteins is to disable chemotaxis until a specific substance “unlocks the door” - or in a more scientific way: induces | ||
+ | intein splicing and enables chemotaxis.<br> | ||
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<h3 class="text-justify">We have created non-natural chemoreceptors, by modifying Tar’s ligand binding domain.</h3> | <h3 class="text-justify">We have created non-natural chemoreceptors, by modifying Tar’s ligand binding domain.</h3> | ||
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<p class="text-center"><b>Fig. 2:</b> Tar chemoreceptor structure. Consists of three main regions: Ligand binding domain (LBD), The HAMP domain and the Cytoplasmic domain.</p> | <p class="text-center"><b>Fig. 2:</b> Tar chemoreceptor structure. Consists of three main regions: Ligand binding domain (LBD), The HAMP domain and the Cytoplasmic domain.</p> | ||
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+ | 1. Bi, S. and Lai, L., 2015. Bacterial chemoreceptors and chemoeffectors. Cellular and Molecular Life Sciences, 72(4), pp.691-708.<br> | ||
+ | <br> | ||
+ | 2. BI, Shuangyu; LAI, Luhua. Bacterial chemoreceptors and chemoeffectors. Cellular and Molecular Life Sciences, 2015, 72.4: 691-708.<br> | ||
+ | <br> | ||
+ | 3. <a href="https://immunology.org/page.aspx?pid=1459" >British Society for Immunology</a><br> | ||
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Revision as of 23:40, 19 October 2016
S.Tar components
S.Tar Introduction
Chemotaxis
is the movement of an organism in response to an external chemical stimulus. The bacterial
chemotaxis system is characterized by specific responses, high sensitivity and a dynamic
range (1). This system enables bacteria to sense their immediate environment and
quickly adapt to changes in its chemical composition - thus fleeing from repellents or moving
towards attractants. The key to this system and the first link in the chain is the bacterial
chemoreceptor - a membrane protein that binds the effector and transduces the signal down
the line.
Despite it's advantages this system is still rather limited, bacterial chemoreceptors have evolved
to sense specific materials that either benefit or harm the cell in some way. The specificity of
a receptor is determined by its ligand binding domain. This domain is the focus of project S.Tar.
S.Tar
The S.Tar platform offers the means to decide what substance will trigger a chemotactic response- controlled chemotaxis. The base of our project and the source of our name is the Tar chemoreceptor, one of four E. coli receptors. By changing Tar’s ligand binding domain to that of other receptors or by mutating it, we show that E. coli can be engineered to respond to completely new materials.
As proof of concept we present two receptors:
1. PctA-Tar ,
a chimera created by replacing the Tar LBD with that of the Pseudomonas receptor PctA.
2. Histamine-Tar,
a receptor created with the help of computational design - using 'Rosetta' bioinformatics
software suite to design mutations in the Tar receptor.
Our attempts did not end here, we also present other attempts to fuse ligand binding
domains:
- LBD from human origin in order to induce chemotaxis towards
Estrogen hormone.
- LBD from a different receptor of E.coli,
Narx receptor,
which is not part of the chemotaxis system.
- A novel lock and key system which relies on
intein proteins. The purpose of these proteins is to disable chemotaxis until a specific substance “unlocks the door” - or in a more scientific way: induces
intein splicing and enables chemotaxis.
We have created non-natural chemoreceptors, by modifying Tar’s ligand binding domain.
References:
1. Bi, S. and Lai, L., 2015. Bacterial chemoreceptors and chemoeffectors. Cellular and Molecular Life Sciences, 72(4), pp.691-708.
2. BI, Shuangyu; LAI, Luhua. Bacterial chemoreceptors and chemoeffectors. Cellular and Molecular Life Sciences, 2015, 72.4: 691-708.
3. British Society for Immunology