Molecular organization, biochemical function, cellular role and evolution of NfuA, an atypical Fe-S carrier

Mol Microbiol. 2012 Oct;86(1):155-71. doi: 10.1111/j.1365-2958.2012.08181.x. Epub 2012 Sep 12.


Biosynthesis of iron-sulphur (Fe-S) proteins is catalysed by multi-protein systems, ISC and SUF. However, 'non-ISC, non-SUF' Fe-S biosynthesis factors have been described, both in prokaryotes and eukaryotes. Here we report in vitro and in vivo investigations of such a 'non-ISC, non SUF' component, the Nfu proteins. Phylogenomic analysis allowed us to define four subfamilies. Escherichia coli NfuA is within subfamily II. Most members of this subfamily have a Nfu domain fused to a 'degenerate' A-type carrier domain (ATC*) lacking Fe-S cluster co-ordinating Cys ligands. The Nfu domain binds a [4Fe-4S] cluster while the ATC* domain interacts with NuoG (a complex I subunit) and aconitase B (AcnB). In vitro, holo-NfuA promotes maturation of AcnB. In vivo, NfuA is necessary for full activity of complex I under aerobic growth conditions, and of AcnB in the presence of superoxide. NfuA receives Fe-S clusters from IscU/HscBA and SufBCD scaffolds and eventually transfers them to the ATCs IscA and SufA. This study provides significant information on one of the Fe-S biogenesis factors that has been often used as a building block by ISC and/or SUF synthesizing organisms, including bacteria, plants and animals.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aconitate Hydratase / metabolism
  • Electron Transport Complex I / metabolism
  • Escherichia coli / enzymology*
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Escherichia coli Proteins / genetics*
  • Escherichia coli Proteins / metabolism*
  • Iron-Sulfur Proteins / genetics*
  • Iron-Sulfur Proteins / metabolism*
  • Phylogeny
  • Protein Binding
  • Protein Interaction Mapping
  • Protein Structure, Tertiary
  • Sequence Homology, Amino Acid


  • Escherichia coli Proteins
  • Iron-Sulfur Proteins
  • NfuA protein, E coli
  • NuoG protein, E coli
  • Aconitate Hydratase
  • Electron Transport Complex I