Figure 9.

In vivo rescue of strain lacking yIsu1 by expression of fIscU. A) Growth of GAL-Isu1/Δisu2 strain transformed with either the empty YCplac22 plasmid or YCplac22 carrying the mitochondrial targeted fIscU gene or the yeast Isu1 gene. Transformants were compared by spotting serial 10-fold dilutions of 10⁶ cells on CSM-TRP/Glucose plates and photographing four days later. yIsu1 and fIscU show equivalent complementing activity. B) Cellular iron uptake for fIscU and yIsu1 complemented GAL-Isu1/Δisu2 strain. The strain with the empty plasmid did not grow and so iron uptake could not be assessed. Iron uptake was measured for 1 hour in sodium citrate buffer. Other mutants served as controls for high uptake activity (nfs1-14) and low uptake activity (Δaft1).