Iron-sulfur (FeS) centers are essential protein cofactors in all forms of life. In particular, FeS centers function as enzyme cofactors in catalysis and electron transfer. Understanding the crosstalk of metal ions on a cellular basis requires multidisciplinary and cooperative approaches that span the entire range from cell and molecular biology, biochemistry, inorganic chemistry, spectroscopy, and structural biology to theory. In the Priority Programme it is planned to study novel enzyme mechanisms, innovative model complexes, and to define the mechanistic basis of the metal center biogenesis pathways in the (patho-)physiological context of living organisms.