UC San Diego

Bacteria are able to survive environments with high concentrations of toxic ionic mercury due to their ability to reduce it to the less toxic neutral species. In order to reduce soluble mercury, bacteria use a subtle mechanism that involves, at least, three proteins. In the periplasm, MerP traps soluble mercury and passes it to a membrane transporter, MerT that introduces mercury to the cytoplasm, where a reductase uses NADPH to convert ionic mercury to the more volatile neutral mercury. The initial trapping of the mercury by MerP and its final reduction by MerA are well understood at the molecular level, however its transport to the cytoplasm by MerT is not understood at the molecular level. We have over expressed and purified the E. coli mercury transporter, MerT, in milligram quantities and identified its dimeric oligomer state by three biochemical techniques: chemical cross-linking, size exclusion chromatography, and analytical ultracentrifugation