Carbon monoxide dehydrogenase (CODH) is found in acetogenic and methanogenic organisms and is responsible for the synthesis and breakdown of acetyl-CoA, respectively. CODH has two types of metal clusters, a cubane [Fe4-S4] center (B-cluster) similar to that of hybrid cluster protein (HCP) and a Ni-Fe-S center (C-cluster) where carbon monoxide oxidation occurs. Bifunctional CODH forms a heterotetramer with acetyl-CoA synthase (ACS) consisting of two CODH and two ACS subunits while monofunctional CODH forms a homodimer. Bifunctional CODH reduces carbon dioxide to carbon monoxide and ACS then synthesizes acetyl-CoA from carbon monoxide, CoA, and a methyl group donated by another protein (CoFeSP), while monofunctional CODH oxidizes carbon monoxide to carbon dioxide. CODH and ACS each have a metal cluster referred to as the C- and A-clusters, respectively.
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