title: The methanogenic CO2 reducing-and-fixing enzyme is bifunctional and contains 46 [4Fe-4S] clusters.
abstract: Biological methane formation starts with a challenging adenosine triphosphate (ATP)-independent carbon dioxide (CO2) fixation process. We explored this enzymatic process by solving the x-ray crystal structure of formyl-methanofuran dehydrogenase, determined here as Fwd(ABCDFG)2and Fwd(ABCDFG)4complexes, from Methanothermobacter wolfeii The latter 800-kilodalton apparatus consists of four peripheral catalytic sections and an electron-supplying core with 46 electronically coupled [4Fe-4S] clusters. Catalysis is separately performed by subunits FwdBD (FwdB and FwdD), which are related to tungsten-containing formate dehydrogenase, and subunit FwdA, a binuclear metal center carrying amidohydrolase. CO2is first reduced to formate in FwdBD, which then diffuses through a 43-angstrom-long tunnel to FwdA, where it condenses with methanofuran to formyl-methanofuran. The arrangement of [4Fe-4S] clusters functions as an electron relay but potentially also couples the four tungstopterin active sites over 206 angstroms.
authors.affiliation: Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Straße 10, 35043 Marburg, Germany.
authors.forename: Tristan
authors.initials: T
authors.lastname: Wagner
authors.affiliation: Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438 Frankfurt am Main, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Ermler
authors.affiliation: Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Straße 10, 35043 Marburg, Germany. shima@mpi-marburg.mpg.de.|Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), 332-0012 Saitama, Japan.
authors.forename: Seigo
authors.initials: S
authors.lastname: Shima
mesh_terms: D000445:Aldehyde Oxidoreductases / Q000737:chemistry*; D000581:Amidohydrolases / Q000737:chemistry; D019843:Archaeal Proteins / Q000737:chemistry*; D055162:Biocatalysis; D002245:Carbon Dioxide / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004958:Estradiol / Q000031:analogs & derivatives; D007506:Iron-Sulfur Proteins / Q000737:chemistry*; D008697:Methane / Q000138:chemical synthesis*; D017016:Methanococcaceae / Q000201:enzymology*; D010084:Oxidation-Reduction; D000072757:Protein Conformation, beta-Strand; D014414:Tungsten / Q000737:chemistry
chemical_list: C521829:11-methoxy-4,16-difluoroestradiol; D019843:Archaeal Proteins; D007506:Iron-Sulfur Proteins; D002245:Carbon Dioxide; D004958:Estradiol; D000445:Aldehyde Oxidoreductases; C060639:formylmethanofuran dehydrogenase; D000581:Amidohydrolases; D008697:Methane; D014414:Tungsten