title: A second soluble Hox-type NiFe enzyme completes the hydrogenase set in Thiocapsa roseopersicina BBS.
abstract: Three functional NiFe hydrogenases were previously characterized in Thiocapsa roseopersicina BBS: two of them are attached to the periplasmic membrane (HynSL and HupSL), and one is localized in the cytoplasm (HoxEFUYH). The ongoing genome sequencing project revealed the presence of genes coding for another soluble Hox-type hydrogenase enzyme (hox2FUYH). Hox2 is a heterotetrameric enzyme; no indication for an additional subunit was found. Detailed comparative in vivo and in vitro activity and expression analyses of HoxEFUYH (Hox1) and the newly discovered Hox2 enzyme were performed. Functional differences between the two soluble NiFe hydrogenases were disclosed. Hox1 seems to be connected to both sulfur metabolism and dark/photofermentative processes. The bidirectional Hox2 hydrogenase was shown to be metabolically active under specific conditions: it can evolve hydrogen in the presence of glucose at low sodium thiosulfate concentration. However, under nitrogen-fixing conditions, it can oxidize H(2) but less than the other hydrogenases in the cell.
authors.affiliation: Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt 62, Szeged 6726, Hungary.
authors.forename: Judit
authors.initials: J
authors.lastname: Maróti
authors.forename: Attila
authors.initials: A
authors.lastname: Farkas
authors.forename: Ildikó K
authors.initials: IK
authors.lastname: Nagy
authors.forename: Gergely
authors.initials: G
authors.lastname: Maróti
authors.forename: Eva
authors.initials: E
authors.lastname: Kondorosi
authors.forename: Gábor
authors.initials: G
authors.lastname: Rákhely
authors.forename: Kornél L
authors.initials: KL
authors.lastname: Kovács
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D020869:Gene Expression Profiling; D005947:Glucose / Q000378:metabolism; D006859:Hydrogen / Q000378:metabolism; D006864:Hydrogenase / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D055503:Protein Multimerization; D017422:Sequence Analysis, DNA; D020616:Thiocapsa roseopersicina / Q000201:enzymology*; D013885:Thiosulfates / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D013885:Thiosulfates; D006859:Hydrogen; C043296:nickel-iron hydrogenase; D006864:Hydrogenase; D005947:Glucose