title: The crystal structure of [Fe]-hydrogenase reveals the geometry of the active site.
abstract: Biological formation and consumption of molecular hydrogen (H2) are catalyzed by hydrogenases, of which three phylogenetically unrelated types are known: [NiFe]-hydrogenases, [FeFe]-hydrogenases, and [Fe]-hydrogenase. We present a crystal structure of [Fe]-hydrogenase at 1.75 angstrom resolution, showing a mononuclear iron coordinated by the sulfur of cysteine 176, two carbon monoxide (CO) molecules, and the sp2-hybridized nitrogen of a 2-pyridinol compound with back-bonding properties similar to those of cyanide. The three-dimensional arrangement of the ligands is similar to that of thiolate, CO, and cyanide ligated to the low-spin iron in binuclear [NiFe]- and [FeFe]-hydrogenases, although the enzymes have evolved independently and the CO and cyanide ligands are not found in any other metalloenzyme. The related iron ligation pattern of hydrogenases exemplifies convergent evolution and presumably plays an essential role in H2 activation. This finding may stimulate the ongoing synthesis of catalysts that could substitute for platinum in applications such as fuel cells.
authors.affiliation: Max-Planck-Institut für Terrestrische Mikrobiologie and Laboratorium für Mikrobiologie, Fachbereich Biologie, Philipps-Universität Marburg, Karl-von-Frisch-Strasse, D-35043 Marburg, Germany. shima@mpi-marburg.mpg.de
authors.forename: Seigo
authors.initials: S
authors.lastname: Shima
authors.forename: Oliver
authors.initials: O
authors.lastname: Pilak
authors.forename: Sonja
authors.initials: S
authors.lastname: Vogt
authors.forename: Michael
authors.initials: M
authors.lastname: Schick
authors.forename: Marco S
authors.initials: MS
authors.lastname: Stagni
authors.forename: Wolfram
authors.initials: W
authors.lastname: Meyer-Klaucke
authors.forename: Eberhard
authors.initials: E
authors.lastname: Warkentin
authors.forename: Rudolf K
authors.initials: RK
authors.lastname: Thauer
authors.forename: Ulrich
authors.initials: U
authors.lastname: Ermler
mesh_terms: D001051:Apoenzymes / Q000737:chemistry; D001665:Binding Sites; D002248:Carbon Monoxide / Q000737:chemistry; D020134:Catalytic Domain; D003067:Coenzymes / Q000737:chemistry; D018360:Crystallography, X-Ray; D003486:Cyanides / Q000737:chemistry / Q000378:metabolism; D019281:Dimerization; D019143:Evolution, Molecular; D020035:Holoenzymes / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry / Q000378:metabolism*; D006864:Hydrogenase / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D007501:Iron / Q000737:chemistry; D008024:Ligands; D008697:Methane / Q000096:biosynthesis; D017015:Methanococcales / Q000201:enzymology*; D008958:Models, Molecular; D010084:Oxidation-Reduction; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary
chemical_list: D001051:Apoenzymes; D003067:Coenzymes; D003486:Cyanides; D020035:Holoenzymes; D008024:Ligands; D002248:Carbon Monoxide; D006859:Hydrogen; D007501:Iron; C043296:nickel-iron hydrogenase; D006864:Hydrogenase; D008697:Methane