CHE.496/2009/Planning: Difference between revisions
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*Try to get the arsenic incorporated into a compound / complex | *Try to get the arsenic incorporated into a compound / complex | ||
**Potentially able to precipitate out of solution? | **Potentially able to precipitate out of solution? | ||
===Pathway=== | ===Pathway=== | ||
Latest revision as of 14:59, 17 May 2009
Arsenic sequestration
Strategies
- Knockout arsA or arsB
- Existing mutant strain: arsB758(del)::kan
- Uncertain whether function is KO
- Upregulate E. coli arsC (arsenate reductase)
- Include copy of the gene on a plasmid, express at rates higher than wt
- Transfer exogenous arsenate reductases to E.coli
- Two families besides the E.coli arsC exist
- Question of whether they are more efficient, require co-enzymes, etc
- Express metal binding peptide in periplasm
- Cys-Gly-Cys-Cys-Gly repeat + fusion to maltose binding protein for localization
- Development of Bacterium-Based Heavy Metal Biosorbents: Enhanced Uptake of Cadmium and Mercury by Escherichia coli Expressing a Metal Binding Motif
- Try to get the arsenic incorporated into a compound / complex
- Potentially able to precipitate out of solution?
Pathway
<html><img src="http://www3.interscience.wiley.com/cgi-bin/fulltext/118914921/nf3"></html>
Genes
- arsA
- Arsenical pump-driving ATPase [ Escherichia coli UMN026 ]
- GeneID: 7155799
- arsB
- arsenite/antimonite transporter [ Escherichia coli str. K-12 substr. DH10B ]
- GeneID: 6062297
- arsC
- arsenate reductase [ Escherichia coli str. K-12 substr. DH10B ]
- GeneID: 6058451
- Protein: Arsenate Reductase (ArsC) family, ArsC subfamily; arsenic reductases similar to that encoded by arsC on the R733 plasmid of Escherichia coli. E. coli ArsC catalyzes the reduction of arsenate [As(V)] to arsenite [As(III)], the first step in the detoxification of arsenic, using reducing equivalents derived from glutathione (GSH) via glutaredoxin (GRX). ArsC contains a single catalytic cysteine, within a thioredoxin fold, that forms a covalent thiolate-As(V) intermediate, which is reduced by GRX through a mixed GSH-arsenate intermediate. This family of predominantly bacterial enzymes is unrelated to two other families of arsenate reductases which show similarity to low-molecular-weight acid phosphatases and phosphotyrosyl phosphatases.
References
- http://ukpmc.ac.uk/picrender.cgi?artid=35130&blobtype=pdf (arsenate inhibits phosphate transport in bacteria)
- http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=106604
- Cadmium and Mercury
- "The development of an immobilized biomass from bacterial cells has been discussed as an approach for the development of heavy metal removal systems (17) and involves the immobilization of nonviable cells or cell remnants containing the metal binding peptide within a suitable matrix. The ultimate utility of such a system will depend on binding capacity, affinity, selectivity, stability, and ease of production, among other factors."
- http://edcsarasotacounty.com/documents/Arsenic%20Speciation%20and%20Toxicity%20Report.pdf
