INTRO TO FE/S CLUSTERS

Proteins that have Fe/S clusters as co-factors play key roles in metabolism, electron transport, and regulation of gene expression. These Fe/S proteins are thought to have developed early in evolution and are therefore virtually found in the cells of all species. Biosynthesis of Fe/Sproteins in eukaryotes takes place primarily in the mitochondria and is inherited by bacteria. The synthesis in the mitochondria is completed by the iron-sulfur cluster assembly (ISC) machinery. The ISC comes from the bacterial ancestor of the organelles and is conserved among eukaryotes that range from low to hi complexity.

Fe/S proteins most frequently contain 2Fe-2s, 3Fe-4S, and 4Fe-4S clusters. "These molecular clusters undergo oxidation-reduction reactions, may be inserted or removed from proteins, can influence protein structure by preferential side chain ligations, and can be interconverted." These clusters have the capacity of readily exchanging electrons and makes iron essential for basic cell functions. It is also a possible catalyst for chemical reactions taht produce free-radicals that lead to cell damage. The importance of iron in these proteins leadds to a highly regulated pathway. Iron homeostasis in mammals is maintained by controling expression of proteins of iron metabolism. Regulation after gene transcriptionis converted by iron regulatory protein 1 and 2 (IRP1 and IRP2). These two regulatory proteins utilize mRNA encoding protein that are involved in uptake, storage, and use iron in all cells of the body.