Team:Freiburg/Description

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(Blue light receptor)
(Green light receptor)
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Sometimes a regulated and coordinated gene expression and therefore protein production is needed.
Sometimes a regulated and coordinated gene expression and therefore protein production is needed.
We decided to use light-controlled gene expression,because light is everywhere and always available.<br/>
We decided to use light-controlled gene expression,because light is everywhere and always available.<br/>
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The green light receptor is a light-sensing system from the cyanobactrium  Synechocystis sp. PCC6803.<br/> It consists of three parts interacting with each other in order to start regulated gene expression.<br/> These parts are the following:
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The green light receptor is a light-sensing system from the cyanobactrium  Synechocystis sp. PCC6803.<br/> It consists of three parts interacting with each other in order to start regulated gene expression.<br/> These parts are the following:[[File:Green light system.jpg|thumb|350px|Green light system]]
The main receptor is  CcaS(1) ,a cyanobacteriochrome. It is made up of a N-terminal transmembrane helix, a cyanobactreria specific  GAF domain, two PAS domains and a C-terminal histidine kinase.  
The main receptor is  CcaS(1) ,a cyanobacteriochrome. It is made up of a N-terminal transmembrane helix, a cyanobactreria specific  GAF domain, two PAS domains and a C-terminal histidine kinase.  
To be fully functional CcaS has to bind the chromophore Phycocyanobilin (PCB) with its GAF-domain.  
To be fully functional CcaS has to bind the chromophore Phycocyanobilin (PCB) with its GAF-domain.  
The GAF domain in this system has the ligation motif Cys-Leu, instead of the usual plant GAF-domain with Cys-His.
The GAF domain in this system has the ligation motif Cys-Leu, instead of the usual plant GAF-domain with Cys-His.
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Its response regulator is CcaR (2), it belongs to the family of OmpR regulators. CcaR consists of an N-terminal receiver domain that can be phosphorylated by CcaS and a C-terminal DNA-binding domain that binds directly to the promoter region of cpcG2 (3). CpcG2 is an atypical phycobilisome which is playing a role in the energy transfer to photosystemI.
Its response regulator is CcaR (2), it belongs to the family of OmpR regulators. CcaR consists of an N-terminal receiver domain that can be phosphorylated by CcaS and a C-terminal DNA-binding domain that binds directly to the promoter region of cpcG2 (3). CpcG2 is an atypical phycobilisome which is playing a role in the energy transfer to photosystemI.
After light of a wavelength of 532 nm is sensed by the CcaS receptor, it changes its conformation. It undergoes autophosphorylation and the phosphate is transferred to the response regulator CcaR. Once phosphorylated, CcaR can bind to the specific promoter region of cpcG and activate gene expression.
After light of a wavelength of 532 nm is sensed by the CcaS receptor, it changes its conformation. It undergoes autophosphorylation and the phosphate is transferred to the response regulator CcaR. Once phosphorylated, CcaR can bind to the specific promoter region of cpcG and activate gene expression.
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[[File:Green light system.jpg|thumb|350px|Green light system]]
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As the green light sensing system was proven by J.J.Tabor to work also in e.coli, our plan is to integrate the genes for CcaS and CcaR into e.coli genome with a BAC (bacterial artificial chromosome). The gene which one wants to be regulated by green light has only to be inserted behind the cpcG2 promotor region and transferred into "our" e.coli strain.
As the green light sensing system was proven by J.J.Tabor to work also in e.coli, our plan is to integrate the genes for CcaS and CcaR into e.coli genome with a BAC (bacterial artificial chromosome). The gene which one wants to be regulated by green light has only to be inserted behind the cpcG2 promotor region and transferred into "our" e.coli strain.
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Revision as of 18:03, 19 September 2011


This is the wiki page
of the Freiburger student
team competing for iGEM 2011.
Thank you for your interest!