You can use the filter on the left to narrow the results
Previous
Type
All Books Papers
Title
Author
Keywords
ISBN
DOI Access
CSIC digital access
Search
Details
PublicationJOURNAL OF THE AMERICAN CHEMICAL SOCIETY
Year2006
Volume128
Pages5209-5218
International

Changing the Ligation of the Distal [4Fe4S] Cluster in NiFe hydrogenase Impars Inter- and Intramolecular Electron Transfers

Authors:Sebastien Dementin , Valerie Belle , Patrick Bertrand , Bruno Guigliarelli , Géraldine Adryanczyk-Perrier , Antonio López de Lacey, Víctor Manuel Fernández López, Marc Rousset , Christophe Leger
Groups of research:BioElectroCatalysis
In NiFe hydrogenases, electrons are transferred from the active site to the redox partner via a chain of three Iron−Sulfur clusters, and the surface-exposed [4Fe4S] cluster has an unusual His(Cys)3 ligation. When this Histidine (H184 in Desulfovibrio fructosovorans) is changed into a cysteine or a glycine, a distal cubane is still assembled but the oxidative activity of the mutants is only 1.5 and 3% of that of the WT, respectively. We compared the activities of the WT and engineered enzymes for H2 oxidation, H+ reduction and H/D exchange, under various conditions:  (i) either with the enzyme directly adsorbed onto an electrode or using soluble redox partners, and (ii) in the presence of exogenous ligands whose binding to the exposed Fe of H184G was expected to modulate the properties of the distal cluster. Protein film voltammetry proved particularly useful to unravel the effects of the mutations on inter and intramolecular electron transfer (ET). We demonstrate that changing the coordination of the distal cluster has no effect on cluster assembly, protein stability, active-site chemistry and proton transfer; however, it slows down the first-order rates of ET to and from the cluster. All-sulfur coordination is actually detrimental to ET, and intramolecular (uphill) ET is rate determining in the glycine variant. This demonstrates that although [4Fe4S] clusters are robust chemical constructs, the direct protein ligands play an essential role in imparting their ability to transfer electrons.
Keywords:
logo de CSIC