title: Bacterial formate hydrogenlyase complex.
abstract: Under anaerobic conditions, Escherichia coli can carry out a mixed-acid fermentation that ultimately produces molecular hydrogen. The enzyme directly responsible for hydrogen production is the membrane-bound formate hydrogenlyase (FHL) complex, which links formate oxidation to proton reduction and has evolutionary links to Complex I, the NADH:quinone oxidoreductase. Although the genetics, maturation, and some biochemistry of FHL are understood, the protein complex has never been isolated in an intact form to allow biochemical analysis. In this work, genetic tools are reported that allow the facile isolation of FHL in a single chromatographic step. The core complex is shown to comprise HycE (a [NiFe] hydrogenase component termed Hyd-3), FdhF (the molybdenum-dependent formate dehydrogenase-H), and three iron-sulfur proteins: HycB, HycF, and HycG. A proportion of this core complex remains associated with HycC and HycD, which are polytopic integral membrane proteins believed to anchor the core complex to the cytoplasmic side of the membrane. As isolated, the FHL complex retains formate hydrogenlyase activity in vitro. Protein film electrochemistry experiments on Hyd-3 demonstrate that it has a unique ability among [NiFe] hydrogenases to catalyze production of H2 even at high partial pressures of H2. Understanding and harnessing the activity of the FHL complex is critical to advancing future biohydrogen research efforts.
authors.affiliation: Division of Molecular Microbiology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland;
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: McDowall
authors.affiliation: Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3QR, United Kingdom; and.
authors.forename: Bonnie J
authors.initials: BJ
authors.lastname: Murphy
authors.affiliation: Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Haumann
authors.affiliation: Division of Molecular Microbiology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland;
authors.forename: Tracy
authors.initials: T
authors.lastname: Palmer
authors.affiliation: Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3QR, United Kingdom; and.
authors.forename: Fraser A
authors.initials: FA
authors.lastname: Armstrong
authors.affiliation: Division of Molecular Microbiology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland; f.sargent@dundee.ac.uk.
authors.forename: Frank
authors.initials: F
authors.lastname: Sargent
mesh_terms: D002384:Catalysis; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D005560:Formate Dehydrogenases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006859:Hydrogen / Q000378:metabolism; D006864:Hydrogenase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D007506:Iron-Sulfur Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D009097:Multienzyme Complexes / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D046912:Multiprotein Complexes / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D007506:Iron-Sulfur Proteins; D009097:Multienzyme Complexes; D046912:Multiprotein Complexes; D006859:Hydrogen; C086230:hycE protein, E coli; D006864:Hydrogenase; D005560:Formate Dehydrogenases; C054017:formate hydrogenlyase
keywords: PFE; bacterial hydrogen metabolism