Sensor

For eliminating copper contaminant automatically , the E.coli is suppose to make response as soon as the concentration of copper is excessive in the environment. Sensing and cooperating with copper ion，some special nucleotide sequences on E.coli chromosome can regulate transcription of downstream.Among those copper-sensing sequences,we will choose the most sensitive、effective sequence as a copper sensor to promote sequential reactions.

Frist，we choose the BEST one.

1. In our project，we put the concentrations on three candidates： MarO（THE marRAB OPERON），an regulon which regulates the multiple antibiotic resistance of E.coli, has been reported as a copper sensor to be controlled by MarR. CopA and CueO ，both of them involves in copper tolerance of E.coli and are activated by CueR in response to excessive concentration of copper .
2. Our standards and methods for choosing the best one
   1. Sensitiveness Through consulting many papers，we draw a conclution that when the concentration of copper reach 1mg/L it can do harm to most plants and animals,and some rules has been issued to restrict the contamination of copper (US EPA stipulate the concentration of drinking water can’t reach 1.3mg/L).Comparing with E.coli copper tolerance,it’s really low concentration（Most E.coli can even bear 100 times of that）.SO our sensor should sensitive enough to sense such low（for E.coli） concentration of copper. Method：
      1. link BBa_E0840 with MarO,pCopA（The promoter of CopA）and pCueO（The promoter of CueO）
      2. set different Cu2+ concentration gradient to test it’s sensitivity through examining the expression of GFP
   2. Effectiveness（specifity） We suppose to apply our E.coli to clean copper in soil，in water and even in animals digestive tract to protect from copper toxical effect.But in complex environment,many metal ions inevitablely exist with copper.For avoiding to send fault information to downstream ,our sensor should be highly specific for copper
   Method：
   1. link BBa_E0840 with MarO,pCopA（The promoter of CopA）and pCueO（The promoter of CueO）individually
   2. use different metal ion to test the specifity of individual sensor.
The most sensitive and specific candidate is what we want.

Second，we link the best sensor to the coding gene which codes T7 polymerase