title: The Na+/H+ antiporter of the thermohalophilic bacterium Rhodothermus marinus.
abstract: In the thermohalophilic bacterium Rhodothermus marinus, the NADH:quinone oxidoreductase (complex I) is encoded by two single genes and two operons, one of which contains the genes for five complex I subunits, nqo10-nqo14, a pterin carbinolamine dehydratase, and a putative single subunit Na+/H+ antiporter. Here we report that the latter encodes indeed a functional Na+/H+ antiporter, which is able to confer resistance to Na+, but not to Li+ to an Escherichia coli strain defective in Na+/H+ antiporters. In addition, an extensive amino acid sequence comparison with several single subunit Na+/H+ antiporters from different groups, namely NhaA, NhaB, NhaC, and NhaD, suggests that this might be the first member of a new type of Na+/H+ antiporters, which we propose to call NhaE.
authors.affiliation: Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, Apartado 127, 2781-901 Oeiras, Portugal.
authors.forename: Ana M P
authors.initials: AM
authors.lastname: Melo
authors.forename: Nuno A M
authors.initials: NA
authors.lastname: Felix
authors.forename: João N
authors.initials: JN
authors.lastname: Carita
authors.forename: Lígia M
authors.initials: LM
authors.lastname: Saraiva
authors.forename: Miguel
authors.initials: M
authors.lastname: Teixeira
mesh_terms: D000595:Amino Acid Sequence; D042967:Electron Transport Complex I / Q000737:chemistry / Q000502:physiology; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000502:physiology; D015964:Gene Expression Regulation, Bacterial; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D045245:Rhodothermus / Q000737:chemistry* / Q000502:physiology*; D017923:Sodium-Hydrogen Exchangers / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D014158:Transcription, Genetic / Q000502:physiology
chemical_list: D029968:Escherichia coli Proteins; C102839:NhaA protein, E coli; D017923:Sodium-Hydrogen Exchangers; D042967:Electron Transport Complex I