Project description:Transcriptome profile of the Hydrogenobacter thermophilus TK-6 cells aerobically or anaerobically grown on ammonium, nitrate, or mix of ammonium and nitrate was determined by NimbleGen Eukaryotic Expression array (4x72K).
Project description:Hydrogenobacter thermophilus Kawasumi et al. 1984 is the type species of the genus Hydrogenobacter. H. thermophilus was the first obligate autotrophic organism reported among aerobic hydrogen-oxidizing bacteria. Strain TK-6(T) is of interest because of the unusually efficient hydrogen-oxidizing ability of this strain, which results in a faster generation time compared to other autotrophs. It is also able to grow anaerobically using nitrate as an electron acceptor when molecular hydrogen is used as the energy source, and able to aerobically fix CO(2)via the reductive tricarboxylic acid cycle. This is the fifth completed genome sequence in the family Aquificaceae, and the second genome sequence determined from a strain derived from the original isolate. Here we describe the features of this organism, together with the complete genome sequence and annotation. The 1,742,932 bp long genome with its 1,899 protein-coding and 49 RNA genes is a part of the Genomic Encyclopedia of Bacteria and Archaea project.
Project description:Hydrogenobacter thermophilus is a thermophilic, obligately chemolithoautotrophic and aerobic hydrogen-oxidizing bacterium. It is unique in its ability to fix carbon dioxide via the reductive tricarboxylic acid cycle under aerobic conditions. It utilizes molecular hydrogen, elemental sulfur, or thiosulfate as the sole energy source. Here, we report the complete genome sequence of H. thermophilus TK-6.
Project description:Glutamate synthases are classified according to their specificities for electron donors. Ferredoxin-dependent glutamate synthases had been found only in plants and cyanobacteria, whereas many bacteria have NADPH-dependent glutamate synthases. In this study, Hydrogenobacter thermophilus, a hydrogen-oxidizing chemoautotrophic bacterium, was shown to possess a ferredoxin-dependent glutamate synthase like those of phototrophs. This is the first observation, to our knowledge, of a ferredoxin-dependent glutamate synthase in a nonphotosynthetic organism. The purified enzyme from H. thermophilus was shown to be a monomer of a 168-kDa polypeptide homologous to ferredoxin-dependent glutamate synthases from phototrophs. In contrast to known ferredoxin-dependent glutamate synthases, the H. thermophilus glutamate synthase exhibited glutaminase activity. Furthermore, this glutamate synthase did not react with a plant-type ferredoxin (Fd3 from this bacterium) containing a [2Fe-2S] cluster but did react with bacterial ferredoxins (Fd1 and Fd2 from this bacterium) containing [4Fe-4S] clusters. Interestingly, the H. thermophilus glutamate synthase was activated by some of the organic acids in the reductive tricarboxylic acid cycle, the central carbon metabolic pathway of this organism. This type of activation has not been reported for any other glutamate synthases, and this property may enable the control of nitrogen assimilation by carbon metabolism.
Project description:Fumarate reductase (FRD) is an enzyme that reduces fumarate to succinate. In many organisms, it is bound to the membrane and uses electron donors such as quinol. In this study, an FRD from a thermophilic chemolithoautotrophic bacterium, Hydrogenobacter thermophilus TK-6, was purified and characterized. FRD activity using NADH as an electron donor was not detected in the membrane fraction but was found in the soluble fraction. The purified enzyme was demonstrated to be a novel type of FRD, consisting of five subunits. One subunit showed high sequence identity to the catalytic subunits of known FRDs. Although the genes of typical FRDs are assembled in a cluster, the five genes encoding the H. thermophilus FRD were distant from each other in the genome. Furthermore, phylogenetic analysis showed that the H. thermophilus FRD was located in a distinct position from those of known soluble FRDs. This is the first report of a soluble NADH-dependent FRD in Bacteria and of the purification of a FRD that operates in the reductive tricarboxylic acid cycle.
Project description:Two novel-type phosphoserine phosphatases (PSPs) with unique substrate specificity from the thermophilic and hydrogen-oxidizing bacterium Hydrogenobacter thermophilus TK-6 have previously been identified. Here, one of the PSPs (iPSP1) was heterologously expressed in Escherichia coli, purified and crystallized. Diffraction-quality crystals were obtained by the sitting-drop vapour-diffusion method using PEG 4000 as the precipitant. Two diffraction data sets with resolution ranges of 45.0-2.50 and 45.0-1.50 Å were collected from a single crystal and were merged to give a highly complete data set. The space group of the crystal was identified as primitive orthorhombic P2(1)2(1)2(1), with unit-cell parameters a = 49.8, b = 73.6, c = 124.3 Å. The calculated Matthews coefficient (V(M) = 2.32 Å(3) Da(-1)) indicated that the crystal contained one iPSP1 complex per asymmetric unit.
