Two tandemly arranged ferredoxin genes in the Hydrogenobacter thermophilus genome: comparative characterization of the recombinant [4Fe-4S] ferredoxins.
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.
Department of Biotechnology, University of Tokyo, Yayoi, Japan.
Takeshi
T
Ikeda
Masahiro
M
Yamamoto
Hiroyuki
H
Arai
Daijiro
D
Ohmori
Masaharu
M
Ishii
Yasuo
Y
Igarashi
D000595:Amino Acid Sequence; D001419:Bacteria / Q000235:genetics* / Q000378:metabolism*; D002874:Chromosome Mapping; D002876:Chromosomes, Bacterial; D005288:Ferredoxins / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics*; D015870:Gene Expression; D016680:Genome, Bacterial; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D005288:Ferredoxins; D011994:Recombinant Proteins