ABC7 can replace yeast Atm1p in its function in the biogenesis of cytosolic Fe/S proteins.

Yeast cells lacking the ATM1 gene (Δatm1 cells19) were transformed with the yeast expression plasmid pRS424-GPD carrying either no DNA insert or coding sequences for wild-type and mutant ATM1 or ABC7 genes as indicated. Cells were grown in minimal media without added iron in the presence of dextrose. To measure the de novo formation of the Fe/S cluster in cytosolic Leu1p, cells were radiolabeled with (⁵⁵Fe) iron for 1 hour.21 After isolation of the cells, an extract was prepared by breaking cells with glass beads. Immunoprecipitation was performed using antiserum raised against Leu1p, and the co-precipitated ⁵⁵Fe was measured by scintillation counting. The data represent the average of 3 independent experiments, and the bars represent the standard error. The data are given relative to the signal obtained after expression of wild-type ATM1. A background signal for immunoprecipitation with preimmune serum was subtracted (approximately 2%).