Role of phosphate-coordinating arginine residues in the thermal stability of uridine phosphorylase from Shewanella oneidensis MR-1.

The role of phosphate-coordinating arginine residues in the thermal stability of uridine phosphorylase from Shewanella oneidensis MR-1 was investigated by mutation analysis. Uridine phosphorylase mutant genes were constructed by site-directed mutagenesis. The enzyme mutants were prepared and isolated, and their kinetic parameters were determined.

Vanadate as a new substrate for nucleoside phosphorylases.

Orthovanadate was shown to serve as a substrate for nucleoside phosphorylases from Escherichia coli, Shewanella oneidensis, Geobacillus stearothermophilus, and Halomonas chromatireducens AGD 8-3. An exception is thymidine phosphorylase from the extremophilic haloalkaliphilic bacterium Halomonas chromatireducens AGD 8-3, which cannot catalyze the vanadolysis of nucleosides. The kinetic parameters of nucleoside vanadolysis were evaluated.

Calorithrix insularis gen. nov., sp. nov., a novel representative of the phylum Calditrichaeota.

A moderately thermophilic, anaerobic bacterium designated as strain KRT was isolated from a shallow-water submarine hydrothermal vent (Kunashir Island, Southern Kurils, Russia). Cells of strain KRT were thin (0.2-0.

Inhibition of free radical scavenging enzymes affects mitochondrial membrane permeability transition during growth and aging of yeast cells.

In this study, we investigated the change in the antioxidant enzymes activity, cell respiration, reactive oxygen species (ROS), and impairment of membrane mitochondria permeability in the Endomyces magnusii yeasts during culture growth and aging. We showed that the transition into stationary phase is the key tool to understanding interaction of these processes. This growth stage is distinguished by two-fold increase in ROS production and respiration rate as compared to those in the logarithmic phase.

The inhibitors of antioxidant cell enzymes induce permeability transition in yeast mitochondria.

In this study we investigated the effects of exogenous and endogenous oxidative stress on mitochondrial membrane permeability transition in yeast cells. E. magnusii yeast was used in the study as it is the only yeast strain possessing a natural high-capacity Са²⁺ transport system.

Isolation and preliminary characterization of new cytochrome c from autotrophic haloalkaliphilic sulfur-oxidizing bacterium Thioalkalivibrio nitratireducens.

New small cytochrome c (TniCYT) was purified from haloalkaliphilic sulfur-oxidizing bacterium Thioalkalivibrio nitratireducens. The protein was analyzed by mass spectrometry as well as using visible, CD and EPR spectroscopy. It was found that TniCYT is a monomer with a molecular mass of 9461 Da which contains two hemes per molecule.

High-resolution structural analysis of a novel octaheme cytochrome c nitrite reductase from the haloalkaliphilic bacterium Thioalkalivibrio nitratireducens.

Bacterial pentaheme cytochrome c nitrite reductases (NrfAs) are key enzymes involved in the terminal step of dissimilatory nitrite reduction of the nitrogen cycle. Their structure and functions are well studied. Recently, a novel octaheme cytochrome c nitrite reductase (TvNiR) has been isolated from the haloalkaliphilic bacterium Thioalkalivibrio nitratireducens.

Molecular and catalytic properties of a novel cytochrome c nitrite reductase from nitrate-reducing haloalkaliphilic sulfur-oxidizing bacterium Thioalkalivibrio nitratireducens.

A highly active cytochrome c nitrite reductase from the haloalkaliphilic sulfur-oxidizing non-ammonifying bacterium Tv. nitratireducens strain ALEN 2 (TvNiR) was isolated and purified to apparent electrophoretic homogeneity. The enzyme catalyzes reductive conversion of nitrite and hydroxylamine to ammonia without release of any intermediates, as well as reduction of sulfite to sulfide.

Anaerobic growth of the haloalkaliphilic denitrifying sulfur-oxidizing bacterium Thialkalivibrio thiocyanodenitrificans sp. nov. with thiocyanate.

Two strains of obligate chemolithoautotrophic sulfur-oxidizing bacteria were isolated from soda-lake sediments by enrichment culture with thiocyanate and nitrate at pH 9.9. The isolates were capable of growth with thiocyanate or thiosulfate as electron donor, either aerobically or anaerobically, and with nitrate or nitrite as electron acceptor.

Complete denitrification in coculture of obligately chemolithoautotrophic haloalkaliphilic sulfur-oxidizing bacteria from a hypersaline soda lake.

Eight anaerobic enrichment cultures with thiosulfate as electron donor and nitrate as electron acceptor were inoculated with sediment samples from hypersaline alkaline lakes of Wadi Natrun (Egypt) at pH 10; however, only one of the cultures showed stable growth with complete nitrate reduction to dinitrogen gas. The thiosulfate-oxidizing culture subsequently selected after serial dilution developed in two phases. Initially, nitrate was mostly reduced to nitrite, with a coccoid morphotype prevailing in the culture.

New enzyme belonging to the family of molybdenum-free nitrate reductases.

A novel molybdenum-free nitrate reductase was isolated from the obligate chemolithoautotrophic and facultative anaerobic, (halo)alkaliphilic sulphur-oxidizing bacterium Thioalkalivibrio nitratireducens strain ALEN 2. The enzyme was found to contain vanadium and haem c as cofactors. Its native molecular mass was determined as 195 kDa, and the enzyme consists of four identical subunits with apparent molecular masses of 57 kDa.