Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:1.7.1.2 (nitrate reductase)
3,861 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A Gram-negative, facultatively anaerobic, rod-shaped, dissimilatory chlorate-reducing bacterium, strain AW-1(T), was isolated from biomass of an anaerobic chlorate-reducing bioreactor. Phylogenetic analysis of the 16S rDNA sequence showed 100% sequence similarity to Pseudomonas stutzeri DSM 50227 and 98.6% sequence similarity to the type strain of P. stutzeri (DSM 5190(T)). The species P. stutzeri possesses a high degree of genotypic and phenotypic heterogeneity. Therefore, eight genomic groups, termed genomovars, have been proposed based upon deltaTm values, which were used to evaluate the quality of the pairing within heteroduplexes formed by DNA-DNA hybridization. In this study, DNA-DNA hybridization between strain AW-1(T) and P. stutzeri strains DSM 50227 and DSM 5190(T) revealed respectively 80.5 and 56.5% similarity. DNA-DNA hybridization between P. stutzeri strains DSM 50227 and DSM 5190(T) revealed 48.4% similarity. DNA-DNA hybridization indicated that strain AW-1(T) is not related at the species level to the type strain of P. stutzeri. However, strain AW-1(T) and P. stutzeri DSM 50227 are related at the species level. The physiological and biochemical properties of strain AW-1(T) and the two P. stutzeri strains were compared. A common characteristic of P. stutzeri strains is the ability to denitrify. However, in growth experiments, strain AW-1(T) could use only chlorate or oxygen as an electron acceptor and not nitrate, perchlorate or bromate. Strain AW-1(T) is the first chlorate-reducing bacterium described that does not possess another oxyanion-reduction pathway. Cell extracts of strain AW-1(T) showed chlorate and bromate reductase activities but not nitrate reductase activity. P. stutzeri strains DSM 50227 and DSM 5190(T) could use nitrate or oxygen as an electron acceptor, but not chlorate. Chlorate reductase activity, in addition to nitrate reductase activity, was detected in cell extracts of both P. stutzeri strains. Chlorite dismutase activity was absent in extracts of both P. stutzeri strains but was present in extracts of strain AW-1(T). Based on the hybridization experiments and the physiological and biochemical data, it is proposed that strain AW-1(T) be classified as a novel species of Pseudomonas, Pseudomonas chloritidismutans sp. nov. The type strain is strain AW-1(T) (= DSM 13592(T) = ATCC BAA-443(T)).
...
PMID:Pseudomonas chloritidismutans sp. nov., a non-denitrifying, chlorate-reducing bacterium. 1250 87

A two-subunit (alphabeta) form of dissimilatory nitrate reductase from Pseudomonas stutzeri strain ZoBell was separated from the membrane-residing gamma-subunit by a heat solubilization step. Here we present an optimized purification protocol leading to a soluble alphabeta form with high specific activity (70 U/mg). The soluble form has the stoichiometry alpha(1)beta(1) consisting of the 130 kDa alpha-subunit and the 58 kDa beta-subunit. We did not observe any proteolytic cleavage in the course of the heat solubilization. The enzyme is competively inhibited by azide, but not by chlorate. It exhibits a K(M) value of 3.2 mM for nitrate. We compare the enzymatic and electron paramagnetic resonance (EPR) spectroscopic properties of the alphabeta form with the alphabetagamma holoenzyme which resides in the membrane and can be prepared by detergent extraction. The nearly identical EPR spectra for the Mo(V) signal of both enzyme preparations show that the active site is unaffected by the heat step. The factors influencing the binding of the alpha- and beta-subunit to the gamma-subunit are discussed.
...
PMID:Pseudomonas stutzeri soluble nitrate reductase alphabeta-subunit is a soluble enzyme with a similar electronic structure at the active site as the inner membrane-bound alphabetagamma holoenzyme. 1252 76

Bacterial cultures capable of reducing nitrate to nitrite, or of complete denitrification, were established from 5, 10, 15 and 20 cm depths of a freshwater sediment. Taxonomic analysis of the 56 isolates using 16S rRNA gene sequences revealed an unexpected species richness, which included representatives of the gamma-Proteobacteria, Bacillus spp., Staphylococcus spp. and members of the Actinobacteria. Gram-positive species tended to predominate in the lower depths of the sediment, where there was evidence of active sulphate respiration. Sequences (from the narG gene) potentially encoding the catalytic subunit of the membrane-associated nitrate reductase were successfully amplified from 46 of the isolates, using a nested PCR with four degenerate primers. NarG sequences clustered into three major groupings that were supported by alternative phylogenetic analyses. The NarG sequences from Gram-positive isolates (according to rRNA gene phylogeny) clustered together within sequences from the low-G+C Gram-positive bacteria. However, this cluster also included two sequences from members of the genus Pseudomonas. Another group contained mostly NarG sequences from the Proteobacteria (according to rRNA gene phylogeny), but also included five sequences from Gram-positive species. The third group of NarG sequences contained three sequences from Gram-positive species. Thus, the NarG-derived phylogeny is not entirely consistent with 16S rRNA-based taxonomy, precluding the use of the narG gene as a taxonomically useful tool for the characterization of nitrate-respiring bacteria. Total DNA was also extracted from the four depth intervals of the sediment sample and used in similar narG amplifications. Most sequences amplified directly from environmental DNA clustered in the Gram-negative group, and none was in the predominantly Gram-positive group. The study also revealed a degree of spatial organization of a nitrate-respiring community in terms of both microbiology and narG sequences.
...
PMID:Characterization of a nitrate-respiring bacterial community using the nitrate reductase gene (narG) as a functional marker. 1257 96

An anaerobic methylotrophic methanogenic enrichment culture, with sustained metabolic characteristics, including that of methanation for over a decade, was the choice of the present study on interspecies interactions. Growth and methanation by the enrichment were suppressed in the presence of antibiotics, and no methanogen grown on methanol could be isolated using stringent techniques. The present study confirmed syntrophic metabolic interactions in this enrichment with the isolation of a strain of Pseudomonas sp. The organism had characteristic metabolic versatility in metabolizing a variety of substrates including alcohols, aliphatic acids, amino acids, and sugars. Anaerobic growth was favoured with nitrate in the growth medium. Cells grown anaerobically with methanol, revealed maximal nitrate reductase activity. Constitutive oxidative activity of the membrane system emerged from the high-specific oxygen uptake and nitrate reductase activities of the aerobically and anerobically grown cells respectively. Cells grown anaerobically on various alcohols effectively oxidized methanol in the presence of flavins, cofactor FAD and the methanogenic cofactor F420, suggesting a constitutive alcohol oxidizing capacity. In cells grown anaerobically on methanol, the rate of methanol oxidation with F420 was three times that of FAD. Efficient utilization of alcohols in the presence of F420 is a novel feature of the present study. The results suggest that utilization of methanol by the mixed culture would involve metabolic interactions between the Pseudomonas sp. and the methanogen(s). Methylotrophic, methanogenic partnership involving an aerobe is a novel feature hitherto unreported among anaerobic syntrophic associations and is of ecological significance
...
PMID:Metabolic characteristics of an aerobe isolated from a methylotrophic methanogenic enrichment culture. 1271 16

Tap water is one of the causative factors of hospital infections. We examined the disinfective potential of electrolysis and mechanism of disinfection, and clarified the disinfective effect of electrolysis on tap water contaminated with bacteria, and discussed its clinical applications. Tap waters artificially contaminated with Pseudomonas aeruginosa, Escherichia coli, Legionella pneumophila, and Staphylococcus aureus could be sterilized by electrolysis at 20-30 mA for 5 min. A high-density suspension (10(6) CFU/ml) of a spore forming bacterium, Bacillus subtilis was not completely sterilized by electrolysis at 50 mA up to 30 min, but a low-density suspension (10(5) CFU/ml) was totally sterilized by electrolysis at 50 mA for 5 min. Electrolyzed P. aeruginosa changed morphologically, that is, there was bleb formation on the cell wall and irregular aggregation of cytoplasmic small granules. Moreover, cytoplasmic enzyme, nitrate reductase, was inactivated by the electrolysis. On the other hand, genomic DNA of the electrolyzed bacteria was not degenerated, therefore, their DNA polymerase activity was not completely inactivated. Consequently, the major agent in electrolysis for bactericidal action was considered to be free chlorine, and the possible bactericidal mechanism was by destruction of bacterial membranes, followed by the aggregation of peripheral cytoplasmic proteins. Electrolysis of tap water for both disinfecting contaminating bacteria and increasing the disinfectant capacity was considered effective with some limitations, particularly against high-density contamination by spore-forming bacteria. In clinical settings, electrolysis of tap water is considered effective to disinfect water for hand washing in operation theatres, and bathing water for immunocompromised hosts.
...
PMID:Evaluation of disinfective potential of reactivated free chlorine in pooled tap water by electrolysis. 1506 56

This work describes an immunological method for detection and quantification in complex environments of the dissimilative nitrate reductase (NRA) responsible for the reduction of nitrate to nitrite, which plays an important role in ecosystem functioning. The alpha-catalytic subunit of the enzyme was purified from the denitrifying strain Pseudomonas fluorescens YT101 and used for the production of polyclonal antibodies. These antibodies were used to detect and quantify the NRA by a chemifluorescence technique on Western blots after separation of total proteins from pure cultures and soil samples. The specificity, detection threshold and reproducibility of the proposed method were evaluated. A soil experiment showed that our method can be applied to complex environmental samples.
...
PMID:Immunological method for direct assessment of the functionality of a denitrifying strain of Pseudomonas fluorescens in soil. 1517 99

The genes encoding membrane-bound nitrate reductase and its locus from Pseudomonas sp. strain MT-1, which is isolated from the sediment of Mariana Trench, were identified. To some extent, the gene organization in the cluster was different from those of other Pseudomonads. Quite interestingly, two genes encoding putative nitrate transporter (narK and narM) showed higher homologies to counterparts of organisms belonging to other genera than those of Pseudomonads. Especially, narM showed no significant homology to the genes for nitrate transporter of Pseudomonads, and was homologous to those of some marine bacteria. Further, arrangements of NarL- and Fnr-binding motifs in the cluster were different from those of P. stutzeri, closely related strain with MT-1. These observations clearly indicated that lateral transfer of genes in nar gene cluster had occurred in deep sea, and it may contribute to bacterial adaptation to environment of there.
...
PMID:Lateral gene transfer in the deep sea of Mariana Trench: identification of nar gene cluster encoding membrane-bound nitrate reductase from Pseudomonas sp. strain MT-1. 1562 58

A total of 1246 Pseudomonas strains were isolated from the rhizosphere of two perennial grasses (Lolium perenne and Molinia coerulea) with different nitrogen requirements. The plants were grown in their native soil under ambient and elevated atmospheric CO2 content (pCO2) at the Swiss FACE (Free Air CO2 Enrichment) facility. Root-, rhizosphere-, and non-rhizospheric soil-associated strains were characterized in terms of their ability to reduce nitrate during an in vitro assay and with respect to the genes encoding the membrane-bound (named NAR) and periplasmic (NAP) nitrate reductases so far described in the genus Pseudomonas. The diversity of corresponding genes was assessed by PCR-RFLP on narG and napA genes, which encode the catalytic subunit of nitrate reductases. The frequency of nitrate-dissimilating strains decreased with root proximity for both plants and was enhanced under elevated pCO2 in the rhizosphere of L. perenne. NAR (54% of strains) as well as NAP (49%) forms were present in nitrate-reducing strains, 15.5% of the 439 strains tested harbouring both genes. The relative proportions of narG and napA detected in Pseudomonas strains were different according to root proximity and for both pCO2 treatments: the NAR form was more abundant close to the root surface and for plants grown under elevated pCO2. Putative denitrifiers harbored mainly the membrane-bound (NAR) form of nitrate reductase. Finally, both narG and napA sequences displayed a high level of diversity. Anyway, this diversity was correlated neither with the root proximity nor with the pCO2 treatment.
...
PMID:Frequency and diversity of nitrate reductase genes among nitrate-dissimilating Pseudomonas in the rhizosphere of perennial grasses grown in field conditions. 1565 Sep 15

In denitrifying bacteria, the concentration of NO is maintained low by a tight control of the expression and activity of nitrite and NO reductases. Regulation involves redox-linked transcription factors, such as those belonging to the CRP-FNR (cAMP receptor protein-fumarate and nitrate reductase regulator) superfamily, which act as oxygen and N-oxide sensors. Given that few members of this superfamily have been characterized in detail, we have cloned, expressed and purified the dissimilative nitrate respiration regulator from Pseudomonas aeruginosa. To gain insights on the structural properties of the dissimilative nitrate respiration regulator, we have also determined the aggregation state of the purified protein and its ability to bind hydrophobic compounds such as 8-anilino-1-naphthalenesulphonic acid.
...
PMID:N-oxide sensing in Pseudomonas aeruginosa: expression and preliminary characterization of DNR, an FNR-CRP type transcriptional regulator. 1566 1

We present a model for diauxic growth of denitrifying bacteria in which nitrate reductase synthesis kinetics dominate the overall growth kinetics. The model is based on the assumption of the existence of a nitrate respiration operon, thereby linking the rate of nitrate uptake to the activity of nitrate reductase. We show that this approach can model diauxic growth of Pseudomonas denitrificans by conducting experiments in which nitrate reductase activity was measured during both lag and ensuing exponential growth phases. We consistently observed the pattern of low nitrate reductase enzyme activity during the lag phase, increasing before the onset of growth. By fitting model parameters we were able to successfully match experimental data for growth, nitrate uptake, and enzyme activity level.
...
PMID:Structured model for denitrifier diauxic growth. 1580 68


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---