title: Tetrathionate stimulated growth of Campylobacter jejuni identifies a new type of bi-functional tetrathionate reductase (TsdA) that is widely distributed in bacteria.
abstract: Tetrathionate (S4 O6 (2-) ) is used by some bacteria as an electron acceptor and can be produced in the vertebrate intestinal mucosa from the oxidation of thiosulphate (S2 O3 (2-) ) by reactive oxygen species during inflammation. Surprisingly, growth of the microaerophilic mucosal pathogen Campylobacter jejuni under oxygen-limited conditions was stimulated by tetrathionate, although it does not possess any known type of tetrathionate reductase. Here, we identify a dihaem cytochrome c (C8j_0815; TsdA) as the enzyme responsible. Kinetic studies with purified recombinant C. jejuni TsdA showed it to be a bifunctional tetrathionate reductase/thiosulphate dehydrogenase with a high affinity for tetrathionate. A tsdA null mutant still slowly reduced, but could not grow on, tetrathionate under oxygen limitation, lacked thiosulphate-dependent respiration and failed to convert thiosulphate to tetrathionate microaerobically. A TsdA paralogue (C8j_0040), lacking the unusual His-Cys haem ligation of TsdA, had low thiosulphate dehydrogenase and tetrathionate reductase activities. Our data highlight a hitherto unrecognized capacity of C. jejuni to use tetrathionate and thiosulphate in its energy metabolism, which may promote growth in the host. Moreover, as TsdA represents a new class of tetrathionate reductase that is widely distributed among bacteria, we predict that energy conserving tetrathionate respiration is far more common than currently appreciated.
authors: Department of Molecular Biology and Biotechnology, The University of Sheffield, Firth Court, Western Bank, Sheffield, S10 2TN, UK.
authors: Yang-Wei
authors: YW
authors: Liu
authors: Kevin
authors: K
authors: Denkmann
authors: Konrad
authors: K
authors: Kosciow
authors: Christiane
authors: C
authors: Dahl
authors: David J
authors: DJ
authors: Kelly
mesh_terms: D000332:Aerobiosis / Q000187:drug effects; D055162:Biocatalysis / Q000187:drug effects; D016123:Campylobacter jejuni / Q000166:cytology / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development*; D045304:Cytochromes c / Q000378:metabolism; D004583:Electrons; D005561:Formates / Q000494:pharmacology; D007700:Kinetics; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D010084:Oxidation-Reduction / Q000187:drug effects; D010088:Oxidoreductases / Q000378:metabolism*; D010100:Oxygen / Q000494:pharmacology; D011994:Recombinant Proteins / Q000378:metabolism; D013057:Spectrum Analysis; D013776:Tetrathionic Acid / Q000494:pharmacology*; D013885:Thiosulfates / Q000494:pharmacology
chemical_list: D005561:Formates; D011994:Recombinant Proteins; D013885:Thiosulfates; D013776:Tetrathionic Acid; D045304:Cytochromes c; D010088:Oxidoreductases; D009247:NADH, NADPH Oxidoreductases; C014227:ferricyanide reductase; C022727:tetrathionate reductase; C432587:thiosulfate dehydrogenase; D010100:Oxygen