View article

[FeFe] hydrogenase (HydA) catalyzes interconversion between 2H⁺ and H₂ at an active site composed of a [4Fe-4S] cluster linked to a 2Fe subcluster that harbors CO, CN⁻ and azapropanedithiolate (adt²⁻) ligands. HydE, HydG and HydF are the maturases specifically involved in the biosynthesis of the 2Fe subcluster. Using ligands synthesized by HydE and HydG, HydF assembles a di-iron precursor of the 2Fe subcluster and transfers it to HydA for maturation. Here we report the first X-ray structure of HydF with its [4Fe-4S] cluster. The cluster is chelated by three cysteines and an exchangeable glutamate, which allows the binding of synthetic mimics of the 2Fe subcluster. [Fe₂(adt)(CO)₄(CN)₂]²⁻ is proposed to be the true di-iron precursor because, when bound to HydF, it matures HydA and displays features in Fourier transform infrared (FTIR) spectra that are similar to those of the native HydF active intermediate …