Two proteins with similarity to IscA are encoded in the genome of the cyanobacteriumSynechocystisPCC 6803. One of them, the product ofslr1417 which accounts for of the total soluble protein ofSynechocystiswas over-expressed inE. coliand purified protein was found to be mainly dimeric and did not contain any with iron ions, cysteine andSynecho-cystisIscS led to the formation of one [2Fe2S] cluster at an IscA dimer as demonstrated (by the binding of about one iron and one sulfide ion per IscA monomer) by UV/Vis, EPR and Mo¨ssbauer spectroscopy
