Hydrogenases are key metalloenzymes for the bioproduction and oxidation of hydrogen with potential biotech applications, such as the generation of bio-based fuel cells. The activity of hydrogenases also improves the energy efficiency of nitrogen fixation by recycling the hydrogen evolved from nitrogenase.
Hydrogen is recognized as an essential energy vector on the low-carbon economy that should be implemented to alleviate the huge problems derived from the massive use of fossil fuels. From a biological point of view, hydrogen is both a fuel for cell metabolism and a way to equilibrate redox balance in fermentative and photosynthetic metabolisms through proton reduction. Hydrogenases are key metalloenzymes for the bioproduction and oxidation of hydrogen with potential biotech applications, such as the generation of bio-based fuel cells. The activity of hydrogenases also improves the energy efficiency of nitrogen fixation by recycling the hydrogen evolved from nitrogenase.
The synthesis of hydrogenases involves a complex series of biochemical reactions to assemble protein subunits and metallic cofactors required for enzyme function through a mechanism still not well understood. A final step in this biosynthetic pathway is the processing of a C-terminal tail (CTT) from its large subunit, thus allowing proper insertion of nickel in the unique NiFe(CN)2CO cofactor present in these enzymes. The interaction of this tail with a dedicated endoprotease is dependent on the presence of the nickel atom which, at the same time, will be a key component of the enzyme active center. The presence of the CTT in the immature enzyme is essential for the adequate assembly of the enzyme.
In this work, a collaborative research involving two groups at the CBGP has carried out
These results obtained allow to get further insight on the biosynthesis of the hydrogenase active site, a key process for biotechnological applications focused on the use of hydrogen as a sustainable energy vector.
In silico modelling of early Ni binding by Rhizobium leguminosarum immature hydrogenase.
The flexibility provided by the disorder of the C-terminal tail (CTT, in red) of hydrogenase large subunit allows capturing of a nickel atom (green sphere) by a pair of glutamate residues (deep blue sticks with oxygen atoms in red): one residue at the CTT and the second one at the N-terminal region of the protein. Left and right: structures before and after the Molecular Dynamics simulation. Cysteines involved in binding of Fe(CN)2CO cofactor precursor (grey sphere with ligands as sticks) or Ni atom in mature enzyme are shown as sticks with S atoms in yellow.
Albareda, M., Pacios, L.F., Palacios, J.M. 2019. Computational analyses, molecular dynamics, and mutagenesis studies of unprocessed form of [NiFe] hydrogenase reveal the role of disorder for efficient enzyme maturation. Biochimica et Biophysica Acta (BBA) - Bioenergetics 1860, 325–340. DOI: 10.1016/j.bbabio.2019.01.001