Maturation of the [NiFe] hydrogenases.
The high degree of similarity that exists between all the [NiFe] hydrogenase operons and the near universality of hydrogen metabolism among microorganisms suggest that the microbial ability to metabolize hydrogen is of great importance and ancient origin. The large number of genes present in these operons, which are mostly involved in the maturation of the structural subunit, is indicative of the complexity of the hydrogenase molecular structure. Two main groups of maturation genes can be differentiated based on the resulting phenotypes when mutated: the 'cis-genes', encoding narrow specificity proteins, are mainly located on the same transcription unit as the structural genes, and the 'trans-genes', encoding broad specificity proteins, are located on a different operon. The maturation of the large subunit starts with the formation of a complex with the chaperone HypC, which remains bound to the amino terminus throughout processing. The ligands CN and CO, which are derived from carbamoylphosphate, are then inserted via HypF and probably other accessory proteins. HypB is responsible for nickel atom delivery in a GTP-hydrolysis-dependent reaction. The last identified step in the large subunit maturation process is proteolytic cleavage at the carboxyl terminus. The possible roles of the other maturation proteins are also discussed.
Casalot
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L
University of Missouri-Columbia, Biochemistry Dept, 117 Schweitzer Hall, Columbia, MO 65211, USA.
Rousset
M
M
D000595:Amino Acid Sequence; D001419:Bacteria / Q000201:enzymology / Q000235:genetics; D001426:Bacterial Proteins / Q000502:physiology; D002352:Carrier Proteins / Q000502:physiology; D019204:GTP-Binding Proteins / Q000502:physiology; D005798:Genes, Bacterial; D006859:Hydrogen / Q000378:metabolism*; D006864:Hydrogenase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007501:Iron / Q000737:chemistry; D018832:Molecular Chaperones / Q000502:physiology; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D009532:Nickel / Q000737:chemistry; D009876:Operon; D011498:Protein Precursors / Q000378:metabolism; D016415:Sequence Alignment; D013045:Species Specificity
D001426:Bacterial Proteins; D002352:Carrier Proteins; C089637:HypB protein, bacteria; C108874:HypC protein, Bacteria; C108878:HypF protein, Bacteria; D018832:Molecular Chaperones; D009097:Multienzyme Complexes; D011498:Protein Precursors; D009532:Nickel; D006859:Hydrogen; D007501:Iron; C043296:nickel-iron hydrogenase; D006864:Hydrogenase; D019204:GTP-Binding Proteins