A multidisciplinary analysis of the as-isolated Escherichia coli SufBC₂D complex reveals the presence of two new iron-sulfur clusters

Abstract

Iron-sulfur (Fe-S) clusters are essential inorganic cofactors dedicated to a wide range of biological functions including electron transfer and catalysis. Specialized multi-protein machineries present in all types of organisms support their biosynthesis. These machineries encompass a scaffold protein on which Fe-S clusters are assembled before being transferred to cellular targets. Here, we describe the first characterization of the native Fe-S cluster of the anaerobically purified SufBC2D scaffold from Escherichia coli by XAS, Mossbauer, UV-visible absorption and EPR spectroscopy. Interestingly, we propose that SufBC2D harbors two types of Fe-S cluster, a [2Fe-2S] cluster with an unprecedented usual coordination and a previously unreported [3Fe-3S] cluster. These data combined with mutagenesis and biochemistry allow to propose ligands for these clusters. These results support the hypothesis that both SufB and SufD are involved in Fe-S cluster ligation and are discussed in the context of Fe-S cluster biogenesis where both [2Fe-2S] and [4Fe-4S] clusters need to mature cellular Fe-S protein targets

Multimodal Spectroscopic Analysis of the Fe–S Clusters of the as-Isolated Escherichia coli SufBC2D Complex

“…The evidence for the existence of this species, although currently obscure, is completely fascinating in the context of Fe–S assembly and more broadly in the field of bioinorganic chemistry. Identification of this species must be considered as a new challenge to the community as well as the identification of the flavin role …”

“…Identification of this species must be considered as a new challenge to the community as well as the identification of the flavin role. 50…”