Archaeal ApbC/Nbp35 homologs function as iron-sulfur cluster carrier proteins

J Bacteriol. 2009 Mar;191(5):1490-7. doi: 10.1128/JB.01469-08. Epub 2008 Dec 29.


Iron-sulfur clusters may have been the earliest catalytic cofactors on earth, and most modern organisms use them extensively. Although members of the Archaea produce numerous iron-sulfur proteins, the major cluster assembly proteins found in the Bacteria and Eukarya are not universally conserved in archaea. Free-living archaea do have homologs of the bacterial apbC and eukaryotic NBP35 genes that encode iron-sulfur cluster carrier proteins. This study exploits the genetic system of Salmonella enterica to examine the in vivo functionality of apbC/NBP35 homologs from three archaea: Methanococcus maripaludis, Methanocaldococcus jannaschii, and Sulfolobus solfataricus. All three archaeal homologs could correct the tricarballylate growth defect of an S. enterica apbC mutant. Additional genetic studies showed that the conserved Walker box serine and the Cys-X-X-Cys motif of the M. maripaludis MMP0704 protein were both required for function in vivo but that the amino-terminal ferredoxin domain was not. MMP0704 protein and an MMP0704 variant protein missing the N-terminal ferredoxin domain were purified, and the Fe-S clusters were chemically reconstituted. Both proteins bound equimolar concentrations of Fe and S and had UV-visible spectra similar to those of known [4Fe-4S] cluster-containing proteins. This family of dimeric iron-sulfur carrier proteins evolved before the archaeal and eukaryal lineages diverged, representing an ancient mode of cluster assembly.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adenosine Triphosphatases / chemistry
  • Adenosine Triphosphatases / genetics
  • Adenosine Triphosphatases / metabolism
  • Amino Acid Sequence
  • Archaeal Proteins* / chemistry
  • Archaeal Proteins* / genetics
  • Archaeal Proteins* / isolation & purification
  • Archaeal Proteins* / metabolism
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • GTP-Binding Proteins / chemistry
  • GTP-Binding Proteins / genetics
  • GTP-Binding Proteins / metabolism
  • Genetic Complementation Test
  • Iron-Sulfur Proteins* / chemistry
  • Iron-Sulfur Proteins* / genetics
  • Iron-Sulfur Proteins* / isolation & purification
  • Iron-Sulfur Proteins* / metabolism
  • Methanococcales* / chemistry
  • Methanococcales* / genetics
  • Methanococcales* / metabolism
  • Methanococcus* / chemistry
  • Methanococcus* / genetics
  • Methanococcus* / metabolism
  • Molecular Sequence Data
  • Mutation
  • Protein Structure, Tertiary
  • Saccharomyces cerevisiae Proteins / chemistry
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Sulfolobus* / chemistry
  • Sulfolobus* / genetics
  • Sulfolobus* / metabolism


  • ApbC protein, Salmonella typhimurium
  • Archaeal Proteins
  • Bacterial Proteins
  • Iron-Sulfur Proteins
  • NBP35 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Adenosine Triphosphatases
  • GTP-Binding Proteins