It is now accepted that the presence of a complex metal center within a metallo-enzyme implies the existence of a specific, tightly controlled mechanism for its biosynthesis. This is ensured by machineries that are most often multi-protein in nature, making them highly topical subjects of study. In this series of lectures, we've looked at the study of iron-sulfur centers, or the case of nitrogenase. This last lecture completes the picture by presenting the maturation systems of hydrogenases, enzymes of great technological interest since they catalyze water-hydrogen interconversion very efficiently and are therefore being explored as catalysts in applications such as electrolyzers and fuel cells. The active sites consist of binuclear complexes of either iron (FeFe) or nickel and iron (NiFe). The latter have the remarkable property of containing diatomic ligands such as carbon monoxide (CO) and cyanide (CN), which are the subject of numerous studies.
In this lecture, we present the various natural machineries for assembling these active sites, including the enzymes that contribute to CO and CN biosynthesis, which remain incompletely understood. This lecture concludes with a result obtained in the laboratory and published in the July 4, 2013 issue of the journal Nature. By combining one of the FeFe site assembly proteins, called HydF, with a synthetic biomimetic complex of these sites, it is possible to produce a hybrid protein that is capable of maturing hydrogenase, without the intervention of the natural biosynthesis machinery. This technological tool opens up new prospects for the production of hydrogenases and their applications in new energy technologies.
