Sulfur transfer from the cysteine desulfurase IscS to SepCysS.
A, E. coli IscS (8 μm; lane 1), M. jannaschii SepCysS (20 μm; lane 2), and the two proteins together (lane 3) were incubated with 150 μm [35S]Cys at 37 °C for 3 h, and then the incubation mixtures were analyzed by SDS-PAGE under nonreducing condition. The left and right panels show the Coomassie-stained gel and the PhosphorImager scan, respectively. The positions of maltose-binding protein-tagged IscS (∼90 kDa) and His-tagged SepCysS (∼45 kDa) are labeled. B, E. coli IscS (4 μm) and M. jannaschii SepCysS (20 μm) were incubated with 150 μm [35S]Cys at 37 °C for 30 min, and then the incubation mixtures were analyzed by SDS-PAGE under nonreducing condition (lane 1) and reducing condition with 1% (v/v) β-mercaptoethanol (lane 2).