Phonon-assisted Electron-proton Transfer in [FeFe] Hydrogenases: Topological Role of Clusters

[FeFe] hydrogenases are enzymes that have acquired a unique capacity to synthesize or consume molecular hydrogen (H). This function relies on a complex catalytic mechanism involving the active site and two distinct electron and proton transfer networks working in concert. By an analysis based on terahertz vibrations of [FeFe] hydrogenase structure, we are able to predict and identify the existence of rate-promoting vibrations at the catalytic site and the coupling with functional residues involved in reported electron and proton transfer networks. Our findings suggest that the positioning of the cluster is influenced by the response of the scaffold to thermal fluctuations, which in turn drives the formation of networks for electron transfer through phonon-assisted mechanisms. Thus, we address the problem of linking the molecular structure to the catalytic function through picosecond dynamics, while raising the functional gain brought by the cofactors or clusters, using the concept of fold-encoded localized vibrations.