Figure 1.

Complementation of E. coli cysH by plant APS reductase requires glutathione. WT refers to the cysH strain carrying wild-type alleles for gshA, gshB, and trxB. The others are cysH strains carrying the designated mutation. The relevant medium nutrient composition is indicated above and below the photographs. The cultures were incubated for 48 h at 30°C. Thiol compounds and APS reductase activity were measured in extracts prepared from the cells grown on +cysteine medium. The concentrations of thiol compounds are given below in nmol per g of fresh weight and APS reductase activity is given in pmol⋅min⁻¹ per mg of protein. WT: GSH = 383, γ-EC not detected, cysteine not detected, and APS reductase = 215. trxB: GSH = 575, γ-EC not detected, cysteine not detected, and APS reductase = 4950. gshA: GSH not detected, γ-EC not detected, cysteine = 10, and APS reductase = 210. gshB: GSH = 6, γ-EC = 70, cysteine = 13, and APS reductase = 225