title: The [4Fe-4S]-cluster coordination of [FeFe]-hydrogenase maturation protein HydF as revealed by EPR and HYSCORE spectroscopies.
abstract: [FeFe] hydrogenases are key enzymes for bio(photo)production of molecular hydrogen, and several efforts are underway to understand how their complex active site is assembled. This site contains a [4Fe-4S]-2Fe cluster and three conserved maturation proteins are required for its biosynthesis. Among them, HydF has a double task of scaffold, in which the dinuclear iron precursor is chemically modified by the two other maturases, and carrier to transfer this unit to a hydrogenase containing a preformed [4Fe-4S]-cluster. This dual role is associated with the capability of HydF to bind and dissociate an iron-sulfur center, due to the presence of the conserved FeS-cluster binding sequence CxHx(46-53)HCxxC. The recently solved three-dimensional structure of HydF from Thermotoga neapolitana described the domain containing the three cysteines which are supposed to bind the FeS cluster, and identified the position of two conserved histidines which could provide the fourth iron ligand. The functional role of two of these cysteines in the activation of [FeFe]-hydrogenases has been confirmed by site-specific mutagenesis. On the other hand, the contribution of the three cysteines to the FeS cluster coordination sphere is still to be demonstrated. Furthermore, the potential role of the two histidines in [FeFe]-hydrogenase maturation has never been addressed, and their involvement as fourth ligand for the cluster coordination is controversial. In this work we combined site-specific mutagenesis with EPR (electron paramagnetic resonance) and HYSCORE (hyperfine sublevel correlation spectroscopy) to assign a role to these conserved residues, in both cluster coordination and hydrogenase maturation/activation, in HydF proteins from different microorganisms.
authors.affiliation: Department of Biology, University of Padova, Viale G. Colombo 3, 35131 Padova, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Berto
authors.forename: Marilena
authors.initials: M
authors.lastname: Di Valentin
authors.forename: Laura
authors.initials: L
authors.lastname: Cendron
authors.forename: Francesca
authors.initials: F
authors.lastname: Vallese
authors.forename: Marco
authors.initials: M
authors.lastname: Albertini
authors.forename: Enrico
authors.initials: E
authors.lastname: Salvadori
authors.forename: Giorgio M
authors.initials: GM
authors.lastname: Giacometti
authors.forename: Donatella
authors.initials: D
authors.lastname: Carbonera
authors.forename: Paola
authors.initials: P
authors.lastname: Costantini
mesh_terms: D001665:Binding Sites; D020134:Catalytic Domain; D004578:Electron Spin Resonance Spectroscopy; D006859:Hydrogen / Q000378:metabolism; D006864:Hydrogenase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D007506:Iron-Sulfur Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D011487:Protein Conformation; D046949:Thermotoga neapolitana / Q000201:enzymology* / Q000254:growth & development
chemical_list: D007506:Iron-Sulfur Proteins; D006859:Hydrogen; C118830:iron hydrogenase; D006864:Hydrogenase