title: How Salmonella oxidises H(2) under aerobic conditions.
abstract: Salmonella enterica serovar Typhimurium is a Gram negative bacterial pathogen and a common cause of food-borne illness. Molecular hydrogen has been shown to be a key respiratory electron donor during infection and H(2) oxidation can be catalysed by three genetically-distinct [NiFe] hydrogenases. Of these, hydrogenases-1 (Hyd-1) and Hyd-2 have well-characterised homologues in Escherichia coli. The third, designated Hyd-5 here, is peculiar to Salmonella and is expressed under aerobic conditions. In this work, Salmonella was genetically modified to enable the isolation and characterisation of Hyd-5. Electrochemical analysis established that Hyd-5 is a H(2)-oxidising enzyme that functions in very low levels of H(2) and sustains this activity in high levels of O(2). In addition, electron paramagnetic resonance spectroscopy of the Hyd-5 isoenzyme reveals a complex paramagnetic FeS signal at high potentials which is comparable to that observed for other O(2)-tolerant respiratory [NiFe] hydrogenases. Taken altogether, Hyd-5 can be classified as an O(2)-tolerant hydrogenase that confers upon Salmonella the ability to use H(2) as an electron donor in aerobic respiration.
authors.affiliation: Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR, England, United Kingdom.
authors.forename: Alison
authors.initials: A
authors.lastname: Parkin
authors.forename: Lisa
authors.initials: L
authors.lastname: Bowman
authors.forename: Maxie M
authors.initials: MM
authors.lastname: Roessler
authors.forename: Rosalind A
authors.initials: RA
authors.lastname: Davies
authors.forename: Tracy
authors.initials: T
authors.lastname: Palmer
authors.forename: Fraser A
authors.initials: FA
authors.lastname: Armstrong
authors.forename: Frank
authors.initials: F
authors.lastname: Sargent
mesh_terms: D000332:Aerobiosis; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D055162:Biocatalysis; D015153:Blotting, Western; D055664:Electrochemical Techniques / Q000379:methods; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D006859:Hydrogen / Q000378:metabolism*; D006864:Hydrogenase / Q000235:genetics / Q000378:metabolism*; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D009876:Operon; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D012486:Salmonella typhimurium / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D007527:Isoenzymes; D021122:Protein Subunits; D006859:Hydrogen; C043296:nickel-iron hydrogenase; D006864:Hydrogenase; D010100:Oxygen