User:James Chappell/Metal ions

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Promoters

Cadmium promoter

  • pCad has been shown to have a dose response to the concentration of cadmium. The lowest threshold pcad response is 10-11 and 10-9 Molar of Cadmium. [1] [2]. Has been shown to work successfully in E.coli but requires the expression of the protein CadC regulatory protein. Note of caution, we need to consider that many bacterium including E.coli have developed mechanisms to actively pump out many of the ions out of the cells. For example, P-type ATPase, ZntA that extrudes Cd(II), Zn(II) and Pb(II) and so we may consider either using KO versions of these or expression ion transport channels.

Mercury Promoter

  • The MerR regulatory protein forms a dimer that binds to the single DNA site in the Mer operon. In the absence of mercury the DNA represses the promoter in the absence of mercury and in the presence of mercury it causes activation of the promoter.

http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=413224 1577681

Lead Promoter

  • Lead response element within E.coli that acts similar to that to the mercuary response element. Like the mercuary and the cadmium these promoters have been used within biosensors. [3]

GFP expressing bacterial biosensor to measure lead contamination in aquatic environment.

Metal Binding Proteins

Cadmium

Transport Proteins

Cadium

  • A manganese transport gene has been previously used previously to transport cadmium in engineeered E.coli. The results of this showed that using this gene cells could increase the transport of cadmium by six times compared to cells without this gene. Wild type E.coli do naturally accumulate cadmium via a zinc transporter, however use of a specific transporter clearly specifically increases uptake significantly.
  • The relative rates of uptake have been shown to be 90% maximal at 15 minutes. [4]
  • Some genes that have been used before include mntA and cdtB. [5].

References

  1. Shetty RS, Deo SK, Shah P, Sun Y, Rosen BP, and Daunert S. Luminescence-based whole-cell-sensing systems for cadmium and lead using genetically engineered bacteria. Anal Bioanal Chem. 2003 May;376(1):11-7. DOI:10.1007/s00216-003-1862-9 | PubMed ID:12734613 | HubMed [1]
  2. Endo G and Silver S. CadC, the transcriptional regulatory protein of the cadmium resistance system of Staphylococcus aureus plasmid pI258. J Bacteriol. 1995 Aug;177(15):4437-41. PubMed ID:7543476 | HubMed [2]
  3. Tauriainen S, Karp M, Chang W, and Virta M. Luminescent bacterial sensor for cadmium and lead. Biosens Bioelectron. 1998 Oct 15;13(9):931-8. PubMed ID:9839381 | HubMed [5]
  4. Kim SK, Lee BS, Wilson DB, and Kim EK. Selective cadmium accumulation using recombinant Escherichia coli. J Biosci Bioeng. 2005 Feb;99(2):109-14. DOI:10.1263/jbb.99.109 | PubMed ID:16233765 | HubMed [3]
  5. Deng X, Yi XE, and Liu G. Cadmium removal from aqueous solution by gene-modified Escherichia coli JM109. J Hazard Mater. 2007 Jan 10;139(2):340-4. DOI:10.1016/j.jhazmat.2006.06.043 | PubMed ID:16890348 | HubMed [4]
All Medline abstracts: PubMed | HubMed