Two tandemly arranged ferredoxin genes in the Hydrogenobacter thermophilus genome: comparative characterization of the recombinant [4Fe-4S] ferredoxins

Biosci Biotechnol Biochem. 2005 Jun;69(6):1172-7. doi: 10.1271/bbb.69.1172.


A thermophilic, obligately chemolithoautotrophic hydrogen-oxidizing bacterium, Hydrogenobacter thermophilus TK-6, assimilates carbon dioxide via the reductive tricarboxylic acid cycle. A gene encoding a ferredoxin involved in this cycle as an electron donor (HtFd1) was cloned and sequenced. Interestingly, another ferredoxin gene (encoding HtFd2) was found in tandem with the HtFd1 gene. These two ferredoxin genes overlapped by four bp, and transcriptional analysis revealed that they are co-transcribed as an operon. The deduced amino acid sequences of HtFd1 and HtFd2 were 42.9% identical and each contained four cysteine residues that serve as probable ligands to an iron-sulfur cluster. Spectroscopic analyses of the purified recombinant ferredoxins heterologously expressed in Escherichia coli indicated that each ferredoxin contains a single [4Fe-4S]2+/1+ cluster.

Publication types

  • Comparative Study

MeSH terms

  • Amino Acid Sequence
  • Bacteria / genetics*
  • Bacteria / metabolism*
  • Chromosome Mapping
  • Chromosomes, Bacterial
  • Ferredoxins / biosynthesis
  • Ferredoxins / chemistry*
  • Ferredoxins / genetics*
  • Gene Expression
  • Genome, Bacterial
  • Recombinant Proteins / biosynthesis
  • Recombinant Proteins / chemistry
  • Sequence Alignment
  • Sequence Homology, Amino Acid


  • Ferredoxins
  • Recombinant Proteins