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A [4Fe–4S]-Fe(CO)(CN)-l-cysteine intermediate is the first organometallic precursor in [FeFe] hydrogenase H-cluster bioassembly

Nature Chemistryvolume 10pages555560 (2018) | Download Citation


Biosynthesis of the [FeFe] hydrogenase active site (the 'H-cluster') requires the interplay of multiple proteins and small molecules. Among them, the radical S-adenosylmethionine enzyme HydG, a tyrosine lyase, has been proposed to generate a complex that contains an Fe(CO)2(CN) moiety that is eventually incorporated into the H-cluster. Here we describe the characterization of an intermediate in the HydG reaction: a [4Fe–4S][(Cys)Fe(CO)(CN)] species, 'Complex A', in which a CO, a CN and a cysteine (Cys) molecule bind to the unique 'dangler' Fe site of the auxiliary [5Fe–4S] cluster of HydG. The identification of this intermediate—the first organometallic precursor to the H-cluster—validates the previously hypothesized HydG reaction cycle and provides a basis for elucidating the biosynthetic origin of other moieties of the H-cluster.

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We thank J. Swartz from Stanford University for providing the E. coli strain overexpressing SoHydG. This work is supported by National Institute of Health (GM104543). Correspondence and requests for materials should be addressed to R.D.B. The authors declare no competing financial interests.

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Author notes

    • Daniel L. M. Suess

    Present address: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA


  1. Department of Chemistry, University of California, Davis, CA, USA

    • Guodong Rao
    • , Lizhi Tao
    • , Daniel L. M. Suess
    •  & R. David Britt


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G.R., L.T., D.L.M.S. and R.D.B. designed the experiments. G.R., L.T. and D.L.M.S. performed the experiments and analysed the data. All the authors contributed to writing the manuscript.

Competing interests

The authors declare no competing interests.

Corresponding author

Correspondence to R. David Britt.

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    Supplementary Methods, Table 1, Spectra, Figures and Notes

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