title: Probing the Solvent Accessibility of the [4Fe-4S] Cluster of the Hydrogenase Maturation Protein HydF from Thermotoga neapolitana by HYSCORE and 3p-ESEEM.
abstract: The catalytic site of [FeFe]-hydrogenase, the "H-cluster", composed of a [4Fe-4S] unit connected by a cysteinyl residue to a [2Fe] center coordinated by three CO, two CN(-), and a bridging dithiolate, is assembled in a complex maturation pathway, at present not fully characterized, involving three conserved proteins, HydG, HydE, and HydF. HydF is a complex enzyme, which is thought to act as a scaffold and carrier for the [2Fe] subunit of the H-cluster. This maturase protein contains itself a [4Fe-4S] cluster binding site, with three conserved cysteine residues and a noncysteinyl fourth ligand. In this work, we have exploited 3p-ESEEM and HYSCORE spectroscopies to get insight into the structure and the chemical environment of the [4Fe-4S] cluster of HydF from the hyperthermophilic organism Thermotoga neapolitana. The nature of the fourth ligand and the solvent accessibility of the active site comprising the [4Fe-4S] cluster are discussed on the basis of the spectroscopic results obtained upon H/D exchange. We propose that the noncysteinyl ligated Fe atom of the [4Fe-4S] cluster is the site where the [2Fe] subcluster precursor is anchored and finally processed to be delivered to the hydrogenase (HydA).
authors.affiliation: Department of Chemical Sciences, University of Padova , Via F. Marzolo 1, 35131 Padova, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Albertini
authors.affiliation: Department of Biomedical Sciences, University of Padova , Viale G. Colombo 3, 35131 Padova, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Berto
authors.affiliation: Department of Biomedical Sciences, University of Padova , Viale G. Colombo 3, 35131 Padova, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Vallese
authors.affiliation: Department of Chemical Sciences, University of Padova , Via F. Marzolo 1, 35131 Padova, Italy.
authors.forename: Marilena
authors.initials: M
authors.lastname: Di Valentin
authors.affiliation: Department of Biology, University of Padova , Viale G. Colombo 3, 35131 Padova, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Costantini
authors.affiliation: Department of Chemical Sciences, University of Padova , Via F. Marzolo 1, 35131 Padova, Italy.
authors.forename: Donatella
authors.initials: D
authors.lastname: Carbonera
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D006864:Hydrogenase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D007506:Iron-Sulfur Proteins / Q000737:chemistry* / Q000378:metabolism; D012997:Solvents / Q000737:chemistry; D046949:Thermotoga neapolitana / Q000201:enzymology*
chemical_list: D007506:Iron-Sulfur Proteins; D012997:Solvents; D006864:Hydrogenase