1. Structural and spectroscopic characterization of CO inhibition of [NiFe]-hydrogenase from Citrobacter sp. S-77.
- Author
-
Imanishi T, Nishikawa K, Taketa M, Higuchi K, Tai H, Hirota S, Hojo H, Kawakami T, Hataguchi K, Matsumoto K, Ogata H, and Higuchi Y
- Subjects
- Bacterial Proteins chemistry, Carbon Monoxide metabolism, Carbon Monoxide pharmacology, Catalytic Domain, Crystallography, X-Ray, Electron Spin Resonance Spectroscopy, Enzyme Inhibitors chemistry, Enzyme Inhibitors metabolism, Enzyme Inhibitors pharmacology, Hydrogenase metabolism, Models, Molecular, Protein Conformation, Spectroscopy, Fourier Transform Infrared, Carbon Monoxide chemistry, Citrobacter enzymology, Hydrogenase antagonists & inhibitors, Hydrogenase chemistry
- Abstract
Hydrogenases catalyze the reversible oxidation of H
2 . Carbon monoxide (CO) is known to be a competitive inhibitor of O2 -sensitive [NiFe]-hydrogenases. Although the activities of some O2 -tolerant [NiFe]-hydrogenases are unaffected by CO, the partially O2 -tolerant [NiFe]-hydrogenase from Citrobacter sp. S-77 (S77-HYB) is inhibited by CO. In this work, the CO-bound state of S77-HYB was characterized by activity assays, spectroscopic techniques and X-ray crystallography. Electron paramagnetic resonance spectroscopy showed a diamagnetic Ni2+ state, and Fourier-transform infrared spectroscopy revealed the stretching vibration of the exogenous CO ligand. The crystal structure determined at 1.77 Å resolution revealed that CO binds weakly to the nickel ion in the Ni-Fe active site of S77-HYB. These results suggest a positive correlation between O2 and CO tolerance in [NiFe]-hydrogenases.- Published
- 2022
- Full Text
- View/download PDF