Part:BBa_K1350006
promoter+RBS(BBa_K608002)+Mdfa
The resistance of Escherichia coli to many drugs simultaneously (multidrug resistance) often involves the expression of membrane transporters (Mdrs);MdfA,the known bacterial MDR transporters probably utilize the membrane potential(Δψ) and/or the proton gradient (ΔpH) as the driving force for drug export.In Escherichia coli, Mdfa are identified to function in maintenance of a stable cytoplasmic pH under conditions of alkaline stress.[1,2,3]
This process is mainly activated by the cross membrane proton electrochemical gradient .changing the electrochemical electric potential of proton built by respiration chain to the cross membrane Na+ electrochemical potential. From research about the Na+/ H+ antiporter of E.coli, mdfa can pump Na+ out of cell when it pumps H+ into cell and ATP is consumed through the process.
Verification experiment on Mdfa
After primer design, pcr and gene sequencing, we linked Mdfa to a strong promoter and RBS(BBa_K608002). Then the product, Mdfa device(BBa_K1350006) has been done.The results shows in the figure below.
Figure 1. Restriction digestion plasmid gel picture
Figure 2.Growth contrast in high pH picture
Culture four concentration gradients of E-coli (Mdfa transformed) and E-coli (BBa_K608002 transformed) in high pH conditions. The dilution proportion from left to right respectively is zero, doubling,10-fold,100-fold. The E-coli transformed Mdfa proves to grow more normally than none Mdfa E-coli.
Figure 3. Chart of OD value of Mdfa device and control group in different pH
</center>
Using OD values to validate the growth of E-coli (with Mdfa) and E-coli (with a promoter and RBS). Compared with the E-coli with a promoter, E-coli with Mdfa grow more actively in pH9.0 to pH9.5. In the pH9.75 to pH10, none of them grow.</center>
Result
The result shows Mdfa does work actively in E-coli ,helping tolerate the high pH conditions in a range from pH 9.0 to Ph 9.5.
Sequence and Features
- 10COMPATIBLE WITH RFC[10]
- 12COMPATIBLE WITH RFC[12]
- 21COMPATIBLE WITH RFC[21]
- 23COMPATIBLE WITH RFC[23]
- 25COMPATIBLE WITH RFC[25]
- 1000COMPATIBLE WITH RFC[1000]
| None |