Team:CIDEB-UANL Mexico/project resistance


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iGEM CIDEB 2014 - Project

Resistance Module

Because our project is a biofilter which allows to remove salt from water, the bacteria needs to survive to extreme environmental conditions which normally it can’t do. We need E. coli to survive a high salinity environment to allow it to capture sodium ions and to remove the salt concentration of the water.

In order to accomplish our project goal, we have to change E. coli metabolism and make it stronger, more resistant and more efficient than in normal E. coli bacteria.

Last discoveries show irrE as a protein capable of change the E. coli metabolism, and giving it the ability to survive to bigger temperatures, bigger UV rays radiation and bigger salt concentration (UCL, 2012).


The protein irrE originates from Deinococcus radiodurans, and initially, this gene provides resistance to radiation. But when transformed in E. coli, it protects it against salt, oxidative and thermal shock. (UCL, 2012) Also, different experiments from different iGEM teams, support the idea of the bigger salt resistance in E. coli with this biobrick.


Image 1. This graph done by UCL iGEM 2012, shows how irrE biobrick increased the salt concentration resistance in E. coli compared with the results from Tu Delf iGEM 2010.

irrE has been demonstrated to up regulate transcription of recA and pprA - genes which encode Recombines A and Radiation Inducible Protein. With respect to salt tolerance, irrE up regulates the production of several stress responsive proteins, protein kinases, metabolic proteins, and detoxification proteins. It also down regulates glycerol degradation. With this global regulatory effect, E. coli becomes more salt tolerant (UCL, 2012).


Image 2. This diagram shows the effect of irrE protein on E. coli metabolism.


Initially, IrrE and L2+AIDA, protein for binding silica (Union module), were joined together in only one circuit, but we needed to separate them because L2+AIDA has not been proved yet and it could affect the correct production of IrrE (see image 3).


Image 3. Circuit for our project and for testing resistance and union modules.

Parts of the Module







In the specific case of our bacteria, it helps to continuously transcribing the irrE gene in order to make bacteria resist high concentration of salt. This promoter has a length of 35 pb (Anderson, 2006).




This specific is RBS based on Elowitz repressilator . It is very common to see in many iGEM projects. It has a length of 12 pb (Mahajan, Marinescu , Chow, Wissner -Gross, & Carr, 2003).


Gene that produces irrE , a substance that changes the bacteria’s metabolism and allows bacteria to survive to extreme conditions, some examples could be high UV rays exposition, or high salt concentration levels in an aquatic environment, oxidative or thermal shock. It has a length of 933pb ( Sohrabi , 2012).



Part made of 6pb responsible for transcription stop (Huang, 206).


The resistance module is very important in our project because it allows the correct function of the bio-filter. Because the objective is to remove the sodium ions from the water, E. CARU, at the beggining of the process, will be surrounded by salt molecules which normally E. coli could not support.

IrrE gives resistance to the high salt concentration of the water, allowing the Nhas gene to function and capture the sodium ions.

Another important aspect in the usage of the IrrE gene, is because the promoter in the Capture module is activated with UV rays at 360 wv, intensity that can cause mutations to the bacterium. IrrE protects E. coli from UV rays and allows the bacteria to their work.

Other teams that used IRRE

UCL 2012: They propose to confer salt tolerance on E. coli by linking the salt tolerance gene encoding the protein irrE (BBa_K729001) to a constitutive promoter (BBa_J23119).


Image 3. Part designed by UCL 2012 for the irrE protein.

Project Zoom In


● Antiquity 2013. (2013, January 31). Part:BBa_B0034. Retrieved from

● Huang, H. (2006, August 30). Part:BBa_B1002. Retrieved August 30, 2014, from

● iGEM2006_Berkeley. (2006, August 24). Part:BBa_J23119. Retrieved April 30, 2014, from

● Sohrabi, B. (2012, June 27). Part:BBa_K729001. Retrieved from

● UCLiGEM Team. (2012). IRRE module. Retrieved March 31, 2014. from

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