title: Discovery of acetylene hydratase activity of the iron-sulphur protein IspH.
abstract: The final step of the methylerythritol phosphate isoprenoid biosynthesis pathway is catalysed by the iron-sulphur enzyme IspH, producing the universal precursors of terpenes: isopentenyl diphosphate and dimethylallyl diphosphate. Here we report an unforeseen reaction discovered during the investigation of the interaction of IspH with acetylene inhibitors by X-ray crystallography, Mößbauer, and nuclear magnetic resonance spectroscopy. In addition to its role as a 2H(+)/2e(-) reductase, IspH can hydrate acetylenes to aldehydes and ketones via anti-Markovnikov/Markovnikov addition. The reactions only occur with the oxidised protein and proceed via η(1)-O-enolate intermediates. One of these is characterized crystallographically and contains a C4 ligand oxygen bound to the unique, fourth iron in the 4Fe-4S cluster: this intermediate subsequently hydrolyzes to produce an aldehyde product. This unexpected side to IspH reactivity is of interest in the context of the mechanism of action of other acetylene hydratases, as well as in the design of antiinfectives targeting IspH.
authors.affiliation: Department of Chemistry, Center for Integrated Protein Science, Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Span
authors.affiliation: Department of Chemistry, 600 South Mathews Avenue, University of Illinois, Urbana, Illinois 61801, USA.
authors.forename: Ke
authors.initials: K
authors.lastname: Wang
authors.affiliation: Center for Biophysics and Computational Biology, 607 South Mathews Avenue, University of Illinois, Urbana, Illinois 61801, USA.
authors.forename: Weixue
authors.initials: W
authors.lastname: Wang
authors.affiliation: Department of Chemistry, 600 South Mathews Avenue, University of Illinois, Urbana, Illinois 61801, USA.
authors.forename: Yonghui
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, Center for Integrated Protein Science, Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany.
authors.forename: Adelbert
authors.initials: A
authors.lastname: Bacher
authors.affiliation: Department of Chemistry, Center for Integrated Protein Science, Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Eisenreich
authors.affiliation: Department of Chemistry, 600 South Mathews Avenue, University of Illinois, Urbana, Illinois 61801, USA.
authors.forename: Kai
authors.initials: K
authors.lastname: Li
authors.affiliation: Department of Physics, Knox College, 2 East South Street, Galesburg, Illinois 61401, USA.
authors.forename: Charles
authors.initials: C
authors.lastname: Schulz
authors.affiliation: Department of Chemistry, 600 South Mathews Avenue, University of Illinois, Urbana, Illinois 61801, USA.|Center for Biophysics and Computational Biology, 607 South Mathews Avenue, University of Illinois, Urbana, Illinois 61801, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Oldfield
authors.affiliation: Department of Chemistry, Center for Integrated Protein Science, Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Groll
mesh_terms: D000114:Acetylene / Q000737:chemistry / Q000378:metabolism*; D000447:Aldehydes / Q000737:chemistry / Q000378:metabolism; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007501:Iron / Q000378:metabolism; D008958:Models, Molecular; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D000447:Aldehydes; D029968:Escherichia coli Proteins; D007501:Iron; D010088:Oxidoreductases; C109866:ispH protein, E coli; D000114:Acetylene