Nucleotide sequence and expression of an operon in Escherichia coli coding for formate hydrogenlyase components.
An 8kb segment of DNA from the 58/59 min region of the E. coli chromosome, which complements the defect of a mutant devoid of hydrogenase 3 activity, has been sequenced. Eight open reading frames were identified which are arranged in a transcriptional unit; all open reading frames were transcribed and translated in vivo in a T7 promoter/polymerase system. Analysis of the amino acid sequences derived from the nucleic acid sequences revealed that one of them, open reading frame 5 (ORF5), exhibits significant sequence similarity to conserved regions of the large subunit from Ni/Fe hydrogenases. Two of the open reading frames (orf2, orf6) code for proteins apparently carrying iron-sulphur clusters of the 4Fe/4S ferredoxin type. The product of one of the open reading frames, orf7, displays extensive sequence similarity with protein G from the chloroplast electron transport chain. ORF3 and ORF4, on the other hand, are extremely hydrophobic proteins with nine and six putative transmembrane helices, respectively. Over a limited hydrophilic sequence stretch, bordered by putative transmembrane areas, ORF3 and ORF4 exhibit homology with subunits 4 and 1 of mitochondrial and plastid NADH-ubiquinol oxidoreductases, respectively. The operon described, therefore, appears to comprise genes for redox carriers linking formate oxidation to proton reduction and for a hydrogenase of hitherto unique composition.
Böhm
R
R
Lehrstuhl für Mikrobiologie, Universität München, FRG.
Sauter
M
M
Böck
A
A
D000445:Aldehyde Oxidoreductases / Q000235:genetics*; D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D004579:Electron Transport / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D005560:Formate Dehydrogenases / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D006864:Hydrogenase / Q000235:genetics*; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000235:genetics*; D009876:Operon / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid
D009097:Multienzyme Complexes; D006864:Hydrogenase; D005560:Formate Dehydrogenases; C054017:formate hydrogenlyase; D000445:Aldehyde Oxidoreductases