Structural insights into the active-ready form of [FeFe]-hydrogenase and mechanistic details of its inhibition by carbon monoxide.
[FeFe]-hydrogenases harbor a {2Fe3S} assembly bearing two CO and two CN- groups, a mu-CO ligand, and a vacant coordination site trans to the mu-CO group. Recent theoretical results obtained studying the isolated {2Fe3S} subsite indicated that one of the CN- ligands can easily move from the crystallographic position to the coordination site trans to the mu-CO group; such an isomerization would have a major impact on substrates and inhibitors binding regiochemistry and, consequently, on the catalytic mechanism. To shed light on this crucial issue, we have carried out hybrid QM/MM and free energy perturbation calculations on the whole enzyme, which demonstrate that the protein environment plays a crucial role and maintains the CN- group fixed in the position observed in the crystal structure; these results strongly support the hypothesis that the vacant coordination site trans to the mu-CO group has a crucial functional relevance both in the context of CO-mediated inhibition of the enzyme and in dihydrogen oxidation/evolution catalysis.
Greco
Claudio
C
Department of Biotechnology and Biosciences, University of Milan-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy.
Bruschi
Maurizio
M
Heimdal
Jimmy
J
Fantucci
Piercarlo
P
De Gioia
Luca
L
Ryde
Ulf
U
D002248:Carbon Monoxide / Q000737:chemistry / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D006864:Hydrogenase / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D007506:Iron-Sulfur Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D008958:Models, Molecular; D015394:Molecular Structure
D004791:Enzyme Inhibitors; D007506:Iron-Sulfur Proteins; D002248:Carbon Monoxide; C118830:iron hydrogenase; D006864:Hydrogenase