Effects of intracellular glutathione on sensitivity of Escherichia coli to mercury and arsenite.

The effect of intracellular glutathione on sensitivity to mercuric cations and arsenite anions was studied in Escherichia coli mutants that lack glutathione (gshA) with or without an additional mutation affecting the osmotregulant trehalose. The absence of glutathione increased cellular sensitivity to both Hg2+ and AsO2-. The double mutant was more sensitive to Hg2+ than the single mutant strain. The addition of plasmid resistance determinants of Hg2+ and AsO2- showed additivity between chromosomal genes and plasmid genes. Mercury resistance was increased in the plasmid-containing cells but not up to the level of wild-type cells. Plasmid arsenite resistance was not expressed in the gshA mutant of E. coli.