A New Role for Nickel in Nature – How Bacteria Convert the Greenhouse Gas CO₂
Researchers from the Humboldt-Universität zu Berlin, the University of Potsdam, and the Technische Universität of Berlin, working within the Excellence Cluster “Unifying Systems in Catalysis (UniSysCat)”, have uncovered how bacteria use two nickel-containing enzymes to convert the greenhouse gas carbon dioxide (CO₂) into energy-rich organic compounds. In two studies, published in Nature Catalysis, the research teams show how the two nickel-containing enzymes, carbon monoxide dehydrogenase (CODH) and acetyl-CoA synthase (ACS), transform CO2 into activated acetic acid. These detailed insights into the mechanism provide new approaches for developing synthetic catalysts that could use CO₂ as a raw material.
Two Enzymes – How Structural Changes Control the Reaction
The investigations focus on two enzymes in which nickel and iron ions are uniquely linked in the active sites: CODH and ACS. These enzymes work hand in hand to first convert CO₂ into carbon monoxide (CO) and then into acetyl-CoA, an activated form of acetic acid. This reaction chain is an essential part of the so-called Wood–Ljungdahl pathway, one of the oldest biological processes for carbon fixation.
In one study, scientists from Humboldt Universität around UniSysCat group leader Holger Dobbek, in collaboration with researchers from TU Berlin (Christian Lorent and Ingo Zebger), demonstrated that the nickel ion in the active site of CODH not only binds CO₂ but also supplies the electrons required for the reaction. This flexibility makes the nickel ion the key player in CO₂ activation and conversion. Using a combination of X-ray diffraction and spectroscopy on CODH crystals, they succeeded for the first time in visualizing all catalytically relevant states with bound reaction partners in the enzyme at atomic resolution. “Since our first structure of Ni-containing carbon monoxide dehydrogenases in 2001, I have wondered why these enzymes need Ni ions. Only our new work provides an answer, which lies in the unusual coordination of nickel,” says Prof. Holger Dobbek, head of the Structural Biology and Biochemistry research group at Humboldt Universität. Yudhajeet Basak, the study’s first author, adds: “By understanding the ancient mechanisms of CO₂ fixation, we can transfer them to the development of novel catalysts that could accelerate the transition to a carbon-neutral industry.”
In a complementary study led by Prof. Petra Wendler, UniSysCat researchers investigated how the binding of small molecules to the nickel center of ACS trigger large-scale structural changes in the enzyme. Using high-resolution cryo-electron microscopy, the, team complemented by researchers from the groups of Holger Dobbek and Silke Leimkühler was able to visualize six previously unknown intermediate states of the enzyme. The results show that the enzymes do not operate as rigid structures; rather, ligand binding induces dynamic movements that control the reaction process.
Relevance for Climate Protection and Sustainable Chemistry
The findings are significant not only for basic research. They may also point the way toward transferring biological principles of catalysis to technical processes. In the future, synthetic catalysts modeled after these enzymes could efficiently convert CO₂ into valuable chemical products – an important contribution to a more sustainable circular economy.
Further information
Publications
Yudhajeet Basak, Christian Lorent, Jae-Hun Jeoung, Ingo Zebger, Holger Dobbek. Metalloradical-driven enzymatic CO2 reduction by a dynamic Ni--Fe cluster. Nature Catalysis (2025) 10.1038/s41929-025-01388-5
Jakob Ruickoldt, Julian Kreibich, Thomas Bick, Jae-Hun Jeoung, Benjamin Duffus, Silke Leimkühler, Holger Dobbek, Petra Wendler. Ligand binding to a Ni--Fe cluster orchestrates conformational changes of the CO-dehydrogenase--acetyl-CoA synthase complex. Nature Catalysis (2025) 10.1038/s41929-025-01365-y
Contacts
Prof. Dr. Holger Dobbek
Institute of Biology, Humboldt-Universität zu Berlin
Tel.: 030 2093-49842
Dr. Christian Lorent
Institute of Chemistry, Technische Universität Berlin
christian.lorent(at)tu-berlin.de
Prof. Dr. Petra Wendler
Institute of Biology and Biochemistry, Universität Potsdam