Theoretical hypothesis in a direct electron transfer between non-interacting Fe-S proteins within an artificial fusion.

Reduction of CO2 to formate utilizing formate dehydrogenases (FDHs) has been attempted biologically and electrochemically. However, the conversion efficiency is very low due to the low energy potential of electron donors and/or electron competition with other electron acceptors. To overcome such a low conversion efficiency, I focused on a direct electron transfer between two unrelated redox enzymes for the efficient reduction of CO2 and utilized the quantum mechanical magnetic properties of the [Fe-S] ([iron-sulfur]) cluster to develop a novel electron path.

Genomic potential and physiological characteristics of C1 metabolism in novel acetogenic bacteria.

Acetogenic bacteria can utilize C1 compounds, such as carbon monoxide (CO), formate, and methanol, via the Wood-Ljungdahl pathway (WLP) to produce biofuels and biochemicals. Two novel acetogenic bacteria of the family ES2 and ES3 were isolated from Eulsukdo, a delta island in South Korea. We conducted whole genome sequencing of the ES strains and comparative genome analysis on the core clusters of WLP with DSM1030 and ATCC8486.

sp. nov., an arginine biosynthesis archaeal species isolated from the Central Indian Ocean ridge.

A strictly anaerobic hyperthermophilic archaeon, designated strain IOH2, was isolated from a deep-sea hydrothermal vent (Onnuri vent field) area on the Central Indian Ocean Ridge. Strain IOH2 showed high 16S rRNA gene sequence similarity to MM 739 (99.42 %), DSM 10322 (99.

Bioconversion of CO to formate by artificially designed carbon monoxide:formate oxidoreductase in hyperthermophilic archaea.

Ferredoxin-dependent metabolic engineering of electron transfer circuits has been developed to enhance redox efficiency in the field of synthetic biology, e.g., for hydrogen production and for reduction of flavoproteins or NAD(P).

Thermococcus indicus sp. nov., a Fe(III)-reducing hyperthermophilic archaeon isolated from the Onnuri Vent Field of the Central Indian Ocean ridge.

A strictly anaerobic, dissimilatory Fe(III)-reducing hyperthermophilic archaeon, designated as strain IOH1, was isolated from a new deep-sea hydrothermal vent (Onnuri Vent Field) area in the Central Indian Ocean ridge. Strain IOH1 showed > 99% 16S rRNA gene sequence similarity with Thermococcus celericrescens TS2 (99.4%) and T.

Paradesulfovibrio onnuriensis gen. nov., sp. nov., a chemolithoautotrophic sulfate-reducing bacterium isolated from the Onnuri vent field of the Indian Ocean and reclassification of Desulfovibrio senegalensis as Paradesulfovibrio senegalensis comb. nov.

An anaerobic, rod-shaped, mesophilic, chemolithoautotrophic, sulfate-reducing bacterial strain IOR2 was isolated from a newly found deep-sea hydrothermal vent (OVF, Onnuri Vent Field) area in the central Indian Ocean ridge (11°24'88″ S 66°25'42″ E, 2021 m water depth). The 16S rRNA gene sequence analysis revealed that the strain IOR2 was most closely related to Desulfovibrio senegalensis BLaC1 (96.7%).

Direct Electron Transfer between the -Encoded Hydrogenase and Thioredoxin Reductase in the Nonmethanogenic Archaeon NA1.

To date, NAD(P)H, ferredoxin, and coenzyme F have been identified as electron donors for thioredoxin reductase (TrxR). In this study, we present a novel electron source for TrxR. In the hyperthermophilic archaeon NA1, the -encoded hydrogenase, a homolog of the F-reducing hydrogenase of methanogens, was demonstrated to interact with TrxR in coimmunoprecipitation experiments and pulldown assays.

A rapid and sensitive enzymatic assay for 2,3-butanediol.

In this study, we developed a rapid and sensitive enzymatic assay for 2,3-butanediol (2,3-BDO) detection. The concentration of 2,3-BDO was determined by measuring the reduction of NADP using 2,3-butanediol dehydrogenase (CL-Bdh). The enzymatic assay could detect as low as 0.

A simple biosynthetic pathway for 2,3-butanediol production in Thermococcus onnurineus NA1.

The biosynthetic pathway of 2,3-butanediol (2,3-BDO) production from pyruvate under anaerobic conditions includes three enzymes: acetolactate synthase (ALS), acetolactate decarboxylase (ALDC), and acetoin reductase (AR). Recently, in anaerobic hyperthermophilic Pyrococcus furiosus, it has been reported that acetoin, a precursor of 2,3-BDO, is produced from pyruvate by ALS through a temperature-dependent metabolic switch. In this study, we first attempted to produce 2,3-BDO from Thermococcus onnurineus NA1 using a simple biosynthetic pathway by two enzymes (ALS and AR) at a high temperature.

Redox regulation of SurR by protein disulfide oxidoreductase in Thermococcus onnurineus NA1.

Protein disulfide oxidoreductases are redox enzymes that catalyze thiol-disulfide exchange reactions. These enzymes include thioredoxins, glutaredoxins, protein disulfide isomerases, disulfide bond formation A (DsbA) proteins, and Pyrococcus furiosus protein disulfide oxidoreductase (PfPDO) homologues. In the genome of a hyperthermophilic archaeon, Thermococcus onnurineus NA1, the genes encoding one PfPDO homologue (TON_0319, Pdo) and three more thioredoxin- or glutaredoxin-like proteins (TON_0470, TON_0472, TON_0834) were identified.

Duodenal Loop Obstruction as an Unusual Cause of Acute Pancreatitis: A Case Series.

Duodenal loop obstruction is an unusual cause of acute pancreatitis. Increased intraluminal pressure hinders pancreatic flow, causing dilatation of the pancreatic duct and inducing acute pancreatitis. We experienced three cases of acute pancreatitis that resulted from duodenal loop obstruction after (1) an esophagectomy with gastric pull-up procedure for esophageal cancer, (2) a gastrectomy with Billroth I reconstruction for gastric cancer, and (3) a gastrojejunostomy for abdominal trauma.

Na+ transport by the A1AO-ATP synthase purified from Thermococcus onnurineus and reconstituted into liposomes.

The ATP synthase of many archaea has the conserved sodium ion binding motif in its rotor subunit, implying that these A1AO-ATP synthases use Na(+) as coupling ion. However, this has never been experimentally verified with a purified system. To experimentally address the nature of the coupling ion, we have purified the A1AO-ATP synthase from T.

One-carbon substrate-based biohydrogen production: microbes, mechanism, and productivity.

Among four basic mechanisms for biological hydrogen (H2) production, dark fermentation has been considered to show the highest hydrogen evolution rate (HER). H2 production from one-carbon (C1) compounds such as formate and carbon monoxide (CO) is promising because formate is an efficient H2 carrier, and the utilization of CO-containing syngas or industrial waste gas may render the industrial biohydrogen production process cost-effective. A variety of microbes with the formate hydrogen lyase (FHL) system have been identified from phylogenetically diverse groups of archaea and bacteria, and numerous efforts have been undertaken to improve the HER for formate through strain optimization and bioprocess development.

Energy conservation by oxidation of formate to carbon dioxide and hydrogen via a sodium ion current in a hyperthermophilic archaeon.

Thermococcus onnurineus NA1 is known to grow by the anaerobic oxidation of formate to CO2 and H2, a reaction that operates near thermodynamic equilibrium. Here we demonstrate that this reaction is coupled to ATP synthesis by a transmembrane ion current. Formate oxidation leads to H(+) translocation across the cytoplasmic membrane that then drives Na(+) translocation.

CO-dependent H2 production by genetically engineered Thermococcus onnurineus NA1.

Hydrogenogenic CO oxidation (CO + H(2)O → CO(2) + H(2)) has the potential for H(2) production as a clean renewable fuel. Thermococcus onnurineus NA1, which grows on CO and produces H(2), has a unique gene cluster encoding the carbon monoxide dehydrogenase (CODH) and the hydrogenase. The gene cluster was identified as essential for carboxydotrophic hydrogenogenic metabolism by gene disruption and transcriptional analysis.

Formate-driven growth coupled with H(2) production.

Although a common reaction in anaerobic environments, the conversion of formate and water to bicarbonate and H(2) (with a change in Gibbs free energy of ΔG° = +1.3 kJ mol(-1)) has not been considered energetic enough to support growth of microorganisms. Recently, experimental evidence for growth on formate was reported for syntrophic communities of Moorella sp.

Identification of a novel class of membrane-bound [NiFe]-hydrogenases in Thermococcus onnurineus NA1 by in silico analysis.

In silico analysis of group 4 [NiFe]-hydrogenases from a hyperthermophilic archaeon, Thermococcus onnurineus NA1, revealed a novel tripartite gene cluster consisting of dehydrogenase-hydrogenase-cation/proton antiporter subunits, which may be classified as the new subgroup 4b of [NiFe]-hydrogenases-based on sequence motifs.

The complete genome sequence of Thermococcus onnurineus NA1 reveals a mixed heterotrophic and carboxydotrophic metabolism.

Members of the genus Thermococcus, sulfur-reducing hyperthermophilic archaea, are ubiquitously present in various deep-sea hydrothermal vent systems and are considered to play a significant role in the microbial consortia. We present the complete genome sequence and feature analysis of Thermococcus onnurineus NA1 isolated from a deep-sea hydrothermal vent area, which reveal clues to its physiology. Based on results of genomic analysis, T.

Critical factors to high thermostability of an alpha-amylase from hyperthermophilic archaeon Thermococcus onnurineus NA1.

Genomic analysis of a hyperthermophilic archaeon, Thermococcus onnurineus NA1 [1], revealed the presence of an open reading frame consisting of 1,377 bp similar to alpha-amylases from Thermococcales, encoding a 458-residue polypeptide containing a putative 25-residue signal peptide. The mature form of the alpha-amylase was cloned and the recombinant enzyme was characterized. The optimum activity of the enzyme occurred at 80 degrees C and pH 5.

Cloning, purification, and characterization of a new DNA polymerase from a hyperthermophilic archaeon, Thermococcus sp. NA1.

Genomic analysis of Thermococcus sp. NA revealed the presence of a 3,927-base-pair (bp) family B-type DNA polymerase gene, TNA1_pol. TNA1_pol, without its intein, was overexpressed in Escherichia coli, purified using metal affinity chromatography, and characterized.