A Permease-Oxidase Complex Involved in High-Affinity Iron Uptake in Yeast

Abstract

Iron must cross biological membranes to reach essential intracellular enzymes. Two proteins in the plasma membrane of yeast—a multicopper oxidase, encoded by the FET3 gene, and a permease, encoded by the FTR1 gene—were shown to mediate high-affinity iron uptake. FET3 expression was required for FTR1 protein to be transported to the plasma membrane. FTR1 expression was required for apo-FET3 protein to be loaded with copper and thus acquire oxidase activity. FTR1 protein also played a direct role in iron transport. Mutations in a conserved sequence motif of FTR1 specifically blocked iron transport.