Selenate reductase activity in Escherichia coli requires Isc iron–sulfur cluster biosynthesis genes

The selenate reductase in Escherichia coli is a multi-subunit enzyme predicted to bind Fe–S clusters. In this study, we examined the iron–sulfur cluster biosynthesis genes that are required for selenate reductase activity. Mutants devoid of either the iscU or hscB gene in the Isc iron–sulfur cluster biosynthesis pathway lost the ability to reduce selenate. Genetic complementation by the wild-type sequences restored selenate reductase activity. The results indicate the Isc biosynthetic system plays a key role in selenate reductase Fe–S cofactor assembly and is essential for enzyme activity.