Application of a Synthetic Ferredoxin‐Inspired [4Fe4S]‐Peptide Maquette as the Redox Partner for an [FeFe]‐Hydrogenase

[4Fe4S]-peptide maquettes have been explored as effective models of FeS proteins, but they also hold untapped potential as tools for synthetic biology. Here we demonstrate the application of these maquettes beyond the modelling of electron transfer in biology by substituting the physiological redox partner of a Clostridium acetobutylicum [FeFe]-hydrogenase with a synthetic ferredoxin mimic to direct this enzyme-mediated H₂-oxidation process.

Abstract

‘Bacterial-type’ ferredoxins host a cubane [4Fe4S]^2+/+ cluster that enables these proteins to mediate electron transfer and facilitate a broad range of biological processes. Peptide maquettes based on the conserved cluster-forming motif have previously been reported and used to model the ferredoxins. Herein we explore the integration of a [4Fe4S]-peptide maquette into a H₂-powered electron transport chain. While routinely formed under anaerobic conditions, we illustrate by electron paramagnetic resonance (EPR) analysis that these maquettes can be reconstituted under aerobic conditions by using photoactivated NADH to reduce the cluster at 240 K. Attempts to tune the redox properties of the iron-sulfur cluster by introducing an Fe-coordinating selenocysteine residue were also explored. To demonstrate the integration of these artificial metalloproteins into a semi-synthetic electron transport chain, we utilize a ferredoxin-inspired [4Fe4S]-peptide maquette as the redox partner in the hydrogenase-mediated oxidation of H₂.

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