Human lipoyl synthase (LIAS) is an enzyme containing two [4Fe–4S] clusters (named FeSRS and FeSaux) involved in the biosynthesis of the lipoyl cofactor. The mechanism by which a [4Fe–4S] cluster… Click to show full abstract
Human lipoyl synthase (LIAS) is an enzyme containing two [4Fe–4S] clusters (named FeSRS and FeSaux) involved in the biosynthesis of the lipoyl cofactor. The mechanism by which a [4Fe–4S] cluster is inserted into LIAS has thus far remained elusive. Here we show that NFU1 and ISCA1 of the mitochondrial iron–sulfur cluster assembly machinery, via forming a heterodimeric complex, are the key factors for the insertion of a [4Fe–4S] cluster into the FeSRS site of LIAS. In this process, the crucial actor is the C-domain of NFU1, which, by exploiting a protein-interaction affinity gradient increasing from ISCA1 to LIAS, drives the cluster to its final destination.
               
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