Engineering an FeFe-hydrogenase: do accessory clusters influence O2 resistance and catalytic bias?

G Caserta, C Papini, A Adamska-Venkatesh, L Pecqueur, C Sommer, E Reijerse, W Lubitz, C Gauquelin, I Meynial-Salles, D Pramanik, V Artero, M Atta, M del Barrio, B Faivre, V Fourmond, C Léger and M Fontecave, J. Am. Chem. Soc., DOI: 10.1021/jacs.8b01689 Publication Date (Web): March 29, 2018

[FeFe]-hydrogenases, HydAs, are unique biocatalysts for proton reduction to H2. However, they suffer from a number of drawbacks for biotechnological applications: size, number and diversity of metal cofactors, oxygen sensitivity. Here we show that HydA from Megasphaera elsdenii (MeHydA) displays significant resistance to O2. Further-more, we produced a shorter version of this enzyme (MeH-HydA), lacking the N-terminal domain harbouring the accessory FeS clusters. As shown by detailed spectroscopic and biochemical characterization, MeH-HydA displays the following interesting properties. First, a functional active site can be assembled in MeH-HydA in vitro, providing the enzyme with excellent hydrogenase activity. Second, the resistance of MeHydA to O2 is conserved in MeH-HydA. Third, MeH-HydA is more biased towards proton reduction than MeHydA, as the result of the truncation changing the rate limiting steps in catalysis. This work shows that it is possible to engineer HydA to generate an active hydrogenase that combines the resistance of the most resistant HydAs and the simplicity of algal HydAs, containing only the H-cluster.

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