Ni,Fe‐Containing Carbon Monoxide Dehydrogenases

Abstract

Carbon monoxide can be used by various aerobic bacteria, anaerobic bacteria, and archaea as their sole source of carbon and energy. Carbon monoxide dehydrogenases (CODHases) are the central enzymes in the use of carbon monoxide by microorganisms and they catalyze the reversible oxidation of carbon monoxide with water to carbon dioxide, two protons and two electrons. Two principal types of CODHases can be distinguished by their metal cofactors, sequences, specific activity, and stability in the presence of dioxygen. Whereas CODHases containing molybdenum, copper, iron, and flavin are found in aerobic bacteria, anaerobic microorganisms utilize oxygen‐sensitive CODHases containing nickel and iron. The active site of Ni,Fe‐containing CODHases harbors an asymmetric [NiFe 4 S 4/5 ] cluster in which an Ni 2+ ion coordinated by three to four sulfur ligands is an integral constituent. A bimetallic site consisting of the Ni 2+ ion and a histidine and cysteine coordinated Fe 2+ ion (ferrous component II), located on one side of the cluster, is responsible for the binding and activation of carbon monoxide and water. In addition to the active site cluster, three [4Fe–S] clusters are found in the homodimer, of which one [4Fe–4S] cluster covalently links the two monomers.

Crystal Structure of the ATP-Dependent Maturation Factor of Ni,Fe-Containing Carbon Monoxide Dehydrogenases

“…18 The active site of Ni, Fe-CODHases contains a [Ni-4Fe-4S] cluster, which activates the substrates CO and water [19][20][21][22] and catalyzes their oxidation to CO 2 , two protons, and two electrons. [23][24][25] The function of CooC had been revealed largely by in vivo studies. Rhodospirillum rubrum cells, which have a deletion in the cooC gene, need 1000-fold-higher nickel concentrations in the medium to synthesize active Ni,Fe-CODH.…”

Oxidoreductases and metal cofactors in the functioning of the earth

“…The carbon monoxide dehydrogenase ( coxL [1ZXI], Figure 2 C) is also a metal-containing oxidoreductase of biogeochemical interest. It uses either a Cu-S-Mo cluster for the aerobic variant or a Cu-Ni or Ni-only cofactor for the anaerobic variant of the enzyme ( codh [1MGJ], Figure 2 D) [ 16 , 17 ]. The Cu-S-Mo cluster associated with the aerobic CODH interacts with a single molybdopterin cytosine dinucleotide (MCN) rather than two (as in the FDH).…”

Oxidoreductases and metal cofactors in the functioning of Earth

“…The Carbon monoxide dehydrogenase (coxL [1ZXI], Figure 2C) is also a metalcontaining oxidoreductase of biogeochemical interest. It uses either a Cu-S-Mo cluster for the aerobic variant or a Cu-Ni or Ni-only cofactor for the anaerobic variant of the enzyme (codh [1MGJ], Figure 2D) [14,15]. The Cu-S-Mo cluster associated with the aerobic CODH interacts with a single molybdopterin cytosine dinucleotide (MCN) rather than two (as in the FDH).…”