Figure 4.

Mitochondrial ferredoxin Yah1p is required for the activity of the cytosolic Fe/S protein Leu1p. (A) Wild-type (WT) cells were grown in minimal medium in the presence of galactose (Gal) or glucose (Glu). For depletion of Yah1p, the Gal-YAH1 cells were cultivated in minimal medium in the presence of glucose for the indicated times. A cell lysate was prepared by breaking the cells with glass beads. The enzyme activities of isopropyl malate isomerase (Leu1p) were measured immediately (29). (B) Aliquots of the cell extracts obtained as described in A were analyzed for the amount of Leu1p by immunostaining.