Methanococcus voltae harbors four gene clusters potentially encoding two [NiFe] and two [NiFeSe] hydrogenases, each of the cofactor F420-reducing or F420-non-reducing types.
Four gene clusters were identified in Methanococcus voltae which probably all encode hydrogenases of the [NiFe] type. One of these contains four genes, including those for the three subunits of the known [NiFeSe] hydrogenase capable of reducing the natural deazaflavin cofactor F420. In a second homologous cluster, the gene encoding the subunit corresponding to that which contains selenium in the known enzyme has a cysteine codon in the relevant position. In addition, two more gene clusters were detected which are very similar both in gene order and sequence to one which encodes a hydrogenase that reduces viologens in Methanobacterium thermoautotrophicum, but whose natural electron acceptor is as yet unknown. Again, in one of these clusters, one of the structural genes, which codes for a hydrogenase subunit containing the putative Ni-binding site, contains a selenocysteine codon. The homologous gene in the other clusters again shows a cysteine codon in the corresponding location. The four gene clusters are closely linked. Those encoding the two selenium-free enzymes are arranged in opposite polarities with a relatively short intergenic region. This arrangement is discussed in terms of a possible joint transcriptional regulation.
Halboth
S
S
Department of Biology, Philipps University, Marburg, FRG.
Klein
A
A
D000595:Amino Acid Sequence; D001483:Base Sequence; D015139:Blotting, Southern; D004269:DNA, Bacterial / Q000235:genetics; D005288:Ferredoxins / Q000235:genetics; D006864:Hydrogenase / Q000235:genetics*; D017017:Methanococcus / Q000235:genetics*; D008969:Molecular Sequence Data; D005810:Multigene Family; D009690:Nucleic Acid Conformation; D010084:Oxidation-Reduction; D016133:Polymerase Chain Reaction; D015183:Restriction Mapping; D012256:Riboflavin / Q000031:analogs & derivatives* / Q000378:metabolism; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic
D004269:DNA, Bacterial; D005288:Ferredoxins; C015084:coenzyme F420; C043296:nickel-iron hydrogenase; C058560:nickel-iron-selenium hydrogenase; D006864:Hydrogenase; D012256:Riboflavin