Abstract
Iron-sulfur (Fe-S) proteins that contain an Fe-S cluster as prosthetic group are widely utilized in organisms for a variety of cellular processes including respiratory and photosynthetic electron transport and in the regulation of gene expression. Previous genetic and biochemical studies have revealed two distinct systems in E. coli responsible for Fe-S cluster biosynthesis, termed ISC and SUF, which are encoded by isc (iscSUA-hscBA-fdx) and suf (sufABCDSE) operons, respectively. From lower to higher eukaryotes, the components of the ISC machinery are found in mitochondria, whereas the SUF machinery is conserved in the plastids of algae and higher plants. We have recently determined the crystal structure of IscU, a key component of the ISC machinery, which revealed a novel asymmetric trimer architecture that harbored only one [2Fe-2S] cluster. In addition, the crystal structure of the SufCD complex led to propose a model whereby the SufBCD complex works in Fe-S cluster biosynthesis.
