A safety cap protects hydrogenase from oxygen attack

Winkler, M. and Duan, J. and Rutz, A. and Felbek, C. and Scholtysek, L. and Lampret, O. and Jaenecke, J. and Apfel, U.-P. and Gilardi, G. and Valetti, F. and Fourmond, V. and Hofmann, E. and Léger, C. and Happe, T.

Volume: 12 Pages:
DOI: 10.1038/s41467-020-20861-2
Published: 2021

[FeFe]-hydrogenases are efficient H2-catalysts, yet upon contact with dioxygen their catalytic cofactor (H-cluster) is irreversibly inactivated. Here, we combine X-ray crystallography, rational protein design, direct electrochemistry, and Fourier-transform infrared spectroscopy to describe a protein morphing mechanism that controls the reversible transition between the catalytic Hox-state and the inactive but oxygen-resistant Hinact-state in [FeFe]-hydrogenase CbA5H of Clostridium beijerinckii. The X-ray structure of air-exposed CbA5H reveals that a conserved cysteine residue in the local environment of the active site (H-cluster) directly coordinates the substrate-binding site, providing a safety cap that prevents O2-binding and consequently, cofactor degradation. This protection mechanism depends on three non-conserved amino acids situated approximately 13 Å away from the H-cluster, demonstrating that the 1st coordination sphere chemistry of the H-cluster can be remote-controlled by distant residues. © 2021, The Author(s).

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