Many essential pathways rely upon oxidoreductase enzymes to shuffle electrons from an electron rich source to an electron sink compound. For example, intracellular resistance to arsenate, a highly toxic heavy metal, often requires a glutathione dependent reductase enzyme which reduces arsenate into arsenite. In an effort to investigate the evolutionary space of glutathione dependent oxdioreductase mechanisms, we developed a screen to identify potential pathways of arsenate resistance in E. coli strains which lack the wild type arsenate reductase enzyme, ArsC. Interestingly, we found that the overexpression of GstB, a glutathione-S-transferase, can reconstitute resistance in E. coli cells sensitive to arsenate. Our evidence suggests that arsenate resistance is uniquely specific to this glutathione transferase, and that overexpression of gstB is most likely involved in a novel pathway for the reduction of Arsenate to Arsenite.

Identification of an E. coli glutathione-S-transferase implicated in the intracellular detoxification of arsenate

245th National Meeting (2013)

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