Regulation of iron acquisition and storage in yeast (360.1)

Abstract

Iron is a required element for all eukaryotes, as the facile ability of iron to gain and loose electrons permits it to participate in a wide variety of oxidation‐reduction reactions. Iron can also donate electrons to oxygen or hydrogen peroxide resulting in the generation of toxic oxygen radicals such as, superoxide anion or hydroxyl radical. Organisms therefore tightly regulate cytosolic iron concentration through regulation of iron acquisition and storage. The budding yeast Saccharomyces cerevisiae has developed mechanisms to coordinate iron storage with iron acquisition. Under iron scarce conditions the transcriptional regulators Aft/2 induces the expression of a suite of genes that encode proteins involved in iron acquisition and utilization. Under iron sufficient conditions Aft1/2 regulated genes are no longer transcribed and a different transcription factor Yap5 induces a set of genes including CCC1, which encodes a vacuolar iron importer. Import of iron into the vacuole reduces cytosolic iron levels. Coordination of the products of these transcription factors is regulated by both transcriptional and post‐transcriptional mechanisms. Most notably, the high and low iron sensitive transcription factors both respond to the mitochondrial production of iron‐sulfur clusters. While there are differences in the molecules responsible for cytosolic iron regulation, coordination of iron acquisition and storage is a consistent finding in all species.