title: Connection between the membrane electron transport system and Hyn hydrogenase in the purple sulfur bacterium, Thiocapsa roseopersicina BBS.
abstract: Thiocapsa. roseopersicina BBS has four active [NiFe] hydrogenases, providing an excellent opportunity to examine their metabolic linkages to the cellular redox processes. Hyn is a periplasmic membrane-associated hydrogenase harboring two additional electron transfer subunits: Isp1 is a transmembrane protein, while Isp2 is located on the cytoplasmic side of the membrane. In this work, the connection of HynSL to various electron transport pathways is studied. During photoautotrophic growth, electrons, generated from the oxidation of thiosulfate and sulfur, are donated to the photosynthetic electron transport chain via cytochromes. Electrons formed from thiosulfate and sulfur oxidation might also be also used for Hyn-dependent hydrogen evolution which was shown to be light and proton motive force driven. Hyn-linked hydrogen uptake can be promoted by both sulfur and nitrate. The electron flow from/to HynSL requires the presence of Isp2 in both directions. Hydrogenase-linked sulfur reduction could be inhibited by a QB site competitive inhibitor, terbutryne, suggesting a redox coupling between the Hyn hydrogenase and the photosynthetic electron transport chain. Based on these findings, redox linkages of Hyn hydrogenase are modeled.
authors.affiliation: Department of Biotechnology, University of Szeged, Közép fasor 52., Szeged 6726, Hungary.
authors.forename: Roland
authors.initials: R
authors.lastname: Tengölics
authors.affiliation: Department of Biotechnology, University of Szeged, Közép fasor 52., Szeged 6726, Hungary.
authors.forename: Lívia
authors.initials: L
authors.lastname: Mészáros
authors.affiliation: Department of Biotechnology, University of Szeged, Közép fasor 52., Szeged 6726, Hungary.
authors.forename: E
authors.initials: E
authors.lastname: Győri
authors.affiliation: Department of Biotechnology, University of Szeged, Közép fasor 52., Szeged 6726, Hungary.
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Doffkay
authors.affiliation: Department of Biotechnology, University of Szeged, Közép fasor 52., Szeged 6726, Hungary; Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt 62., Szeged 6726, Hungary.
authors.forename: Kornél L
authors.initials: KL
authors.lastname: Kovács
authors.affiliation: Department of Biotechnology, University of Szeged, Közép fasor 52., Szeged 6726, Hungary; Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt 62., Szeged 6726, Hungary. Electronic address: rakhely@brc.hu.
authors.forename: Gábor
authors.initials: G
authors.lastname: Rákhely
mesh_terms: D055162:Biocatalysis; D015153:Blotting, Western; D004579:Electron Transport; D006864:Hydrogenase / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism*; D011522:Protons; D020616:Thiocapsa roseopersicina / Q000378:metabolism*
chemical_list: D026901:Membrane Transport Proteins; D011522:Protons; D006864:Hydrogenase
keywords: Electron transport; Hydrogenases; Photosynthesis; Photosynthetic bacteria; Sulfur metabolism; Thiocapsa roseopersicina