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Allochromatium vinosum is a photosynthetic, diazotrophic purple sulfur bacterium that oxidizes reduced sulfur compounds hydrogen sulfide, elemental sulfur and thiosulfide. In this article, we report the presence of rnf genes in Allochromatium vinosum, some of which have been reported to take part in nitrogen fixation in some species. | Turk J Biol 30 (2006) 143-147 © TÜB‹TAK Rnf Genes in Purple Sulfur Bacterium Allochromatium vinosum H. Benan D‹NÇTÜRK*, Volkan DEM‹R Department of Molecular Biology and Genetics, Faculty of Science and Letters, ‹stanbul Technical University, Maslak 34469 ‹stanbul - TURKEY Received: 05.01.2006 Abstract: Allochromatium vinosum is a photosynthetic, diazotrophic purple sulfur bacterium that oxidizes reduced sulfur compounds hydrogen sulfide, elemental sulfur and thiosulfide. In this article, we report the presence of rnf genes in Allochromatium vinosum, some of which have been reported to take part in nitrogen fixation in some species. Key Words: rnfG, rnfE, Allochromatium vinosum, purple sulfur bacteria, nitrogen fixation Mor Kükürt Bakterisi Allochromatium vinosum’da Bulunan Rnf Genleri Özet: Allochromatium vinosum fotosentetik, diazotrof, hidrojen sülfit, elementer sülfür ve tiyosülfit gibi kükürtlü bileflikleri yükseltgeyen bir mor kükürt bakterisidir. Bu makalede, baz› organizmalarda azot fiksasyonunda görev alan rnf genlerinin, Allochromatium vinosum‘da varl›¤›n› gösteriyoruz. Anahtar Sözcükler: rnfG, rnfE, Allochromatium vinosum, mor kükürt bakterisi, azot fiksasyonu Introduction Nitrogen fixation is a widespread characteristic of many anoxygenic phototrophic bacteria. Many photosynthetic bacteria from aquatic and terrestrial habitats, including purple sulfur and non-sulfur bacteria, reduce atmospheric dinitrogen to ammonia (1). The majority of nitrogen fixation reactions are catalyzed by molybdenum-containing nitrogenase, which is composed of 2 proteins: Dinitrogenase, the MoFe protein encoded by nifD and nifK genes (2), and dinitrogenase reductase, the Fe protein encoded by the nifH gene (3). The latter contains a [4Fe-4S] cluster and the Fe protein transfers electrons to Mo-Fe protein (4). In R. capsulatus, a set of genes called rnf (an abbreviation of Rhodobacter nitrogen fixation) have also been shown to be required for the function of nitrogenases .
