Maturation of the [FeFe]-Hydrogenase: Direct Transfer of the ( kappa 3 -cysteinate)Fe II (CN)(CO) 2 Complex B from HydG to HydE.
Omeiri, J., Martin, L., Usclat, A., Cherrier, M.V., Nicolet, Y.(2023) Angew Chem Int Ed Engl 62: e202314819-e202314819
- PubMed: 37962296 
- DOI: https://doi.org/10.1002/anie.202314819
- Primary Citation of Related Structures:  
8QMK, 8QML, 8QMM, 8QMN - PubMed Abstract: 
[FeFe]-hydrogenases efficiently catalyze the reversible oxidation of molecular hydrogen. Their prowess stems from the intricate H-cluster, combining a [Fe 4 S 4 ] center with a binuclear iron center ([2Fe] H ). In the latter, each iron atom is coordinated by a CO and CN ligand, connected by a CO and an azadithiolate ligand. The synthesis of this active site involves a unique multiprotein assembly, featuring radical SAM proteins HydG and HydE. HydG initiates the transformation of L-tyrosine into cyanide and carbon monoxide to generate complex B, which is subsequently transferred to HydE to continue the biosynthesis of the [2Fe] H -subcluster. Due to its instability, complex B isolation for structural or spectroscopic characterization has been elusive thus far. Nevertheless, the use of a biomimetic analogue of complex B allowed circumvention of the need for the HydG protein during in vitro functional investigations, implying a similar structure for complex B. Herein, we used the HydE protein as a nanocage to encapsulate and stabilize the complex B product generated by HydG. Using X-ray crystallography, we successfully determined its structure at 1.3 Å resolution. Furthermore, we demonstrated that complex B is directly transferred from HydG to HydE, thus not being released into the solution post-synthesis, highlighting a transient interaction between the two proteins.
Organizational Affiliation: 
Univ. Grenoble-Alpes, CEA, CNRS, IBS, Metalloproteins Unit, 38000, Grenoble, France.