title: Evidence for acyl-iron ligation in the active site of [Fe]-hydrogenase provided by mass spectrometry and infrared spectroscopy.
abstract: [Fe]-hydrogenase catalyzes the reversible heterolytic cleavage of H(2) and stereo-specific hydride transfer to the substrate methenyltetrahydromethanopterin in methanogenic archaea. This enzyme contains a unique iron guanylylpyridinol (FeGP) cofactor as a prosthetic group. It has recently been proposed-on the basis of crystal structural analyses of the [Fe]-hydrogenase holoenzyme-that the FeGP cofactor contains an acyl-iron ligation, the first one reported in a biological system. We report here that the cofactor can be reversibly extracted with acids; its exact mass has been determined by electrospray ionization Fourier transform ion cyclotron resonance mass-spectrometry. The measured mass of the intact cofactor and its gas-phase fragments are consistent with the proposed structure. The mass of the light decomposition products of the cofactor support the presence of acyl-iron ligation. Attenuated total reflection infrared spectroscopy of the FeGP cofactor revealed a band near wave number 1700 cm(-1), which was assigned to the C=O (double bond) stretching mode of the acyl-iron ligand.
authors.affiliation: Max-Planck-Institut für terrestrische Mikrobiologie, Karl-von-Frisch-Straße 10, 35043, Marburg, Germany. shima@mpi-marburg.mpg.de
authors.forename: Seigo
authors.initials: S
authors.lastname: Shima
authors.forename: Michael
authors.initials: M
authors.lastname: Schick
authors.forename: Jörg
authors.initials: J
authors.lastname: Kahnt
authors.forename: Kenichi
authors.initials: K
authors.lastname: Ataka
authors.forename: Klaus
authors.initials: K
authors.lastname: Steinbach
authors.forename: Uwe
authors.initials: U
authors.lastname: Linne
mesh_terms: D001105:Archaea / Q000737:chemistry / Q000201:enzymology; D019843:Archaeal Proteins / Q000737:chemistry; D020134:Catalytic Domain; D006864:Hydrogenase / Q000737:chemistry* / Q000378:metabolism; D007501:Iron / Q000737:chemistry*; D007506:Iron-Sulfur Proteins / Q000737:chemistry* / Q000378:metabolism; D013058:Mass Spectrometry / Q000379:methods*; D015394:Molecular Structure; D013055:Spectrophotometry, Infrared / Q000379:methods*
chemical_list: D019843:Archaeal Proteins; D007506:Iron-Sulfur Proteins; D007501:Iron; C118830:iron hydrogenase; D006864:Hydrogenase