X-ray Crystallography and Vibrational Spectroscopy Reveal the Key Determinants of Biocatalytic Dihydrogen Cycling by [NiFe] Hydrogenases.

ABSTRACT: [NiFe] hydrogenases are complex model enzymes for the reversible cleavage of dihydrogen (H₂ ). However, structural determinants of efficient H₂ binding to their [NiFe] active site are not properly understood. Here, we present crystallographic and vibrational-spectroscopic insights into the unexplored structure of the H₂ -binding [NiFe] intermediate. Using an F₄₂₀ -reducing [NiFe]-hydrogenase from Methanosarcina barkeri as a model enzyme, we show that the protein backbone provides a strained chelating scaffold that tunes the [NiFe] active site for efficient H₂ binding and conversion. The protein matrix also directs H₂ diffusion to the [NiFe] site via two gas channels and allows the distribution of electrons between functional protomers through a subunit-bridging FeS cluster. Our findings emphasize the relevance of an atypical Ni coordination, thereby providing a blueprint for the design of bio-inspired H₂ -conversion catalysts.

SUBMITTER: Ilina Y 

PROVIDER: S-EPMC6916344 | biostudies-literature | 2019 Dec

REPOSITORIES: biostudies-literature