Influence of FdsC and FdhD on l-cysteine desulfurase activity.

l-cysteine desulfurase activity was measured by determination of total sulfide produced [48]. A) 1 μM IscS from E. coli was mixed with either 2 μM FdhD/FdhD variants or FdsC/FdsC variants and incubated for 10 min in the presence of 1 mM l-cysteine at 30°C. The activity of IscS alone was set to 1. B) l-cysteine desulfurase IscS (1 μM) from E. coli or NifS4, NifS3 and NifS2-Δ1–188 from R. capsulatus (2 μM) were mixed in a 1:2 ratio with FdsC, FdhD or SufE, respectively and incubated for 10 min in the presence of 1 mM l-cysteine at 30°C. The fold induction of IscS, NifS4, NifS3 or NifS2-Δ1–188 activity by incubation with FdsC, FdhD or SufE is relative to the activity of the l-cysteine desulfurase alone, respectively. Kinetic Data are mean values from three independent measurements (±S.D.).