Maturation of the [FeFe]-Hydrogenase: Direct Transfer of the (κ 3 -cysteinate)Fe II (CN)(CO) 2 Complex B from HydG to HydE

• Published in: Angewandte Chemie International Edition Vol. 62; no. 51; p. e202314819
• Main Authors: Omeiri, Juneina, Martin, Lydie, Usclat, Anthony, Cherrier, Mickael V, Nicolet, Yvain
• Format: Journal Article
• Language: English
• Published: Germany 18.12.2023
• Subjects: Electron Spin Resonance Spectroscopy; Ferrous Compounds - metabolism; Hydrogenase - metabolism; Iron - chemistry; Iron-Sulfur Proteins - chemistry; Ligands; Proteins - metabolism; Nanocages; H-Cluster; Iron-Sulfur Clusters; Radical SAM Proteins; Metalloproteins
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202314819

[FeFe]-hydrogenases efficiently catalyze the reversible oxidation of molecular hydrogen. Their prowess stems from the intricate H-cluster, combining a [Fe S ] center with a binuclear iron center ([2Fe] ). 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] -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.