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| Title | Beyond Canonical CO Oxidation: Structural and Evolutionary Insights Into a Non-Canonical Carbon Monoxide Dehydrogenase. |
|---|---|
| Journal, issue, pages | Angew Chem Int Ed Engl, Page e1702233, Year 2026 |
| Publish date | Jul 24, 2026 |
Authors | Maximilian Böhm / Vivek Srinivas / Benjamin Wiseman / Ping Huang / Moritz Senger / Martin Högbom / Henrik Land / ![]() |
| PubMed Abstract | Carbon monoxide dehydrogenases (CODHs) catalyse the reversible oxidation of CO to CO and play central roles in microbial carbon metabolism. While well-characterised CODHs from different phylogenetic ...Carbon monoxide dehydrogenases (CODHs) catalyse the reversible oxidation of CO to CO and play central roles in microbial carbon metabolism. While well-characterised CODHs from different phylogenetic backgrounds exhibit high bidirectional activity, the enigmatic clade B remains functionally uncharacterised. Here, we present the first structural and biochemical characterisation of a clade B CODH from Ruminococcus flavefaciens (RfCODH). It reveals striking divergence from canonical enzymes. A new anaerobic cryo-EM workflow was developed, carried out entirely under anoxic conditions by manual blotting and plunge freezing. It resulted in a 2.53 Å RfCODH structure. The structure adopts the typical CODH fold, but exhibits blocked gas channels, a compromised proton transfer pathway and disrupted cofactor coordination. This provides a structural rationale for RfCODH's severely attenuated CO oxidation activity (13 mU/mg vs. 900 U/mg for the well-studied ChCODH-II). EPR spectroscopy reveals unique oxidised C-cluster states not previously characterised in CODHs. Mirror tree analysis hints to co-evolution between clade B CODHs and associated ABC transporter substrate-binding proteins, suggesting these enzymes function in metabolism of substrates imported via the ABC transporter module. All findings indicate evolutionary repurposing of the CODH scaffold for alternative physiological functions. |
External links | Angew Chem Int Ed Engl / PubMed:42495917 |
| Methods | EM (single particle) |
| Resolution | 2.55 Å |
| Structure data | EMDB-56604, PDB-28lw: |
| Chemicals | ![]() ChemComp-SF4: |
| Source |
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Keywords | OXIDOREDUCTASE / carbon monoxide dehydrogenase / CODH / metalloenzyme / iron sulfur protein / anaerobic enzyme |
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ruminococcus flavefaciens atcc 19208 (bacteria)
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