Arsonoacetate Degradation Pathway Map

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This pathway was contributed by Guang Yao, University of Minnesota.

Organoarsenicals can be used in agricultural applications as animal feed additives, cotton defoliants and post-emergence grass herbicides. Extensive research has been undertaken on the mechanism and extent of arsenic bioalkylation. However, still not much is known on the environmental fate of organoarsenicals. Quinn and McMullan (1995) found that strain ASV2, a Gram-negative bacterium isolated from activated sludge, can utilize arsonoacetate as sole carbon and energy source. This is the first report of a microorganism capable of utilizing a compound containing the carbon-arsenic bonds. In the cells of ASV2, arsonoacetate is degraded into arsenite and acetate in C-As bond cleavage reaction. Since arsenite is more toxic than arsenate, it is oxidized to arsenate by arsenite oxidase as an effective means of detoxification. By contrast, some bacteria, such as Escherichia coli and Staphylococcus aureus, are able to reduce arsenate to arsenite. This reaction is catalyzed by arsenate reductase, an enzyme encoded in plasmids in those bacterial cells.

The following is a text-format arsonoacetate pathway map. Organisms which can initiate the pathway are given, but other organisms may also carry out later steps. Follow the links for more information on compounds or reactions. This map is also available in graphic (4k) format.

             
             Arsonoacetate
                   |   
                   |
                   | A
                   |
                   |
                   v
       Arsenite    +    Acetate
          |^               |
          ||               |
 arsenite || arsenate      |
  oxidase || reductase     |
          ||               |
          v|               v
       Arsenate       Intermediary
       E. coli         Metabolism
      S. aureus          (KEGG)


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Page Author(s): Guang Yao

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