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  • Perspective
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Bioassembly of complex iron–sulfur enzymes: hydrogenases and nitrogenases

Abstract

Nature uses multinuclear metal clusters to catalyse a number of important multielectron redox reactions. Examples that employ complex Fe–S clusters in catalysis include the Fe–Mo cofactor (FeMoco) of nitrogenase and its V and all-Fe variants, and the [FeFe] and [NiFe] hydrogenases. This Perspective begins with a focus on the catalytic H-cluster of [FeFe] hydrogenase, which is highly active in producing molecular H2. There has been much recent progress in characterizing the enzyme-catalysed assembly of the H-cluster, including information gleaned from spectroscopy combined with in vitro isotopic labelling of this cluster using chemical synthesis. We then compare the lessons learned from H-cluster biosynthesis to what is known about the bioassembly of the binuclear active site of [NiFe] hydrogenase and the nitrogenase active site cluster FeMoco.

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Fig. 1: The [FeFe] hydrogenase H-cluster and its biosynthetic origins.
Fig. 2: Reactions carried out by the radical SAM maturase HydG.
Fig. 3: Transfer of S/Se from the HydG synthon to make the adt2− bridge.
Fig. 4: The CNC component of the azadithiolate is sourced from serine.
Fig. 5: Aerobic bioassembly of the [NiFe] hydrogenase (Cys)2Ni(μ-Cys)2Fe(CO)(CN)2 active site.
Fig. 6: Bioassembly of the nitrogenase M-cluster.

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Acknowledgements

This work is funded by the National Institutes of Health (1R35GM126961 to R.D.B.).

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Britt, R.D., Rao, G. & Tao, L. Bioassembly of complex iron–sulfur enzymes: hydrogenases and nitrogenases. Nat Rev Chem 4, 542–549 (2020). https://doi.org/10.1038/s41570-020-0208-x

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