Biosynthesis of complex iron-sulfur enzymes.

Recent advances in our understanding of the mechanisms for the biosynthesis of the complex iron-sulfur (Fe-S) containing prosthetic groups associated with [FeFe]-hydrogenases and nitrogenases have revealed interesting parallels. The biosynthesis of the H-cluster ([FeFe]-hydrogenase) and the FeMo-co (nitrogenase) occurs through a coordinated process that involves the modification of Fe-S cluster precursors synthesized by the general host cell machinery (Isc/Suf). Key modifications to the Fe-S precursors are introduced by the activity of radical S-adenosylmethionine (SAM) enzymes on unique scaffold proteins. The transfer of the modified clusters to a cofactor-less structural apo-protein completes maturation. Together these features provide the basis for establishing unifying paradigms for complex Fe-S cluster biosynthesis for these enzymes.