scholarly journals The role of Ynt1 in nitrate and nitrite transport in the yeastHansenula polymorpha

Yeast ◽  
2004 ◽  
Vol 21 (3) ◽  
pp. 265-276 ◽  
Author(s):  
Felix Machín ◽  
Braulio Medina ◽  
Francisco J. Navarro ◽  
M. Dolores Pérez ◽  
Marten Veenhuis ◽  
...  
Keyword(s):  
Nitrite Transport ◽  
Nitrate And Nitrite

Transcriptional regulation of a hybrid cluster (prismane) protein

2005 ◽  
Vol 33 (1) ◽  
pp. 195-197 ◽  
Author(s):  
N.A. Filenko ◽  
D.F. Browning ◽  
J.A. Cole
Keyword(s):  
Physiological Function ◽  
Response Regulator ◽  
Anaerobic Growth ◽  
Hybrid Cluster ◽  
E Coli ◽  
Mutant Strains ◽  
Translation Initiation Codon ◽  
Nitric Oxide Reduction ◽  
Nitrate And Nitrite

HCP (hybrid-cluster protein) contains two Fe/S clusters, one of which is a hybrid [4Fe-2S-2O] cluster. Despite intensive study, its physiological function has not been reported. The Escherichia coli hcp gene is located in a two-gene operon with hcr, which encodes an NADH-dependent HCP reductase. E. coli HCP is detected after anaerobic growth with nitrate or nitrite: possible roles for it in hydroxylamine or nitric oxide reduction have been proposed. To study the regulation and role of HCP, an hcp::lacZ fusion was constructed and transformed into fnr, arcA and norR mutant strains of E. coli. Transcription from the hcp promoter was induced during anaerobic growth. Only the fnr mutant was defective in hcp expression. Nitrate- and nitrite-induced transcription from the hcp promoter was activated by the response regulator proteins NarL and NarP. Gel retardation assays were used to show that FNR (fumarate-nitrate regulation) and NarL form a complex with the hcp promoter. Transcription of the hcp-hcr operon initiates at a thymine nucleotide located 31 bp upstream of the translation-initiation codon. HCP has been overexpressed from a recombinant plasmid for physiological studies.

scholarly journals NasFED Proteins Mediate Assimilatory Nitrate and Nitrite Transport in Klebsiella oxytoca(pneumoniae) M5al

1998 ◽  
Vol 180 (5) ◽  
pp. 1311-1322 ◽  
Author(s):  
Qitu Wu ◽  
Valley Stewart
Keyword(s):  
Binding Protein ◽  
Klebsiella Oxytoca ◽  
Nitrogen Sources ◽  
Nitrate Transport ◽  
Periplasmic Binding Protein ◽  
Sequence Comparisons ◽  
Abc Protein ◽  
Nitrite Transport ◽  
Dependent Transport ◽  
Nitrate And Nitrite

ABSTRACT Klebsiella oxytoca can use nitrate and nitrite as sole nitrogen sources. The enzymes required for nitrate and nitrite assimilation are encoded by the nasFEDCBA operon. We report here the complete nasFED sequence. Sequence comparisons indicate that the nasFED genes encode components of a conventional periplasmic binding protein-dependent transport system consisting of a periplasmic binding protein (NasF), a homodimeric intrinsic membrane protein (NasE), and a homodimeric ATP-binding cassette (ABC) protein (NasD). The NasF protein and the related NrtA and CmpA proteins of cyanobacteria contain leader (signal) sequences with the double-arginine motif that is hypothesized to direct prefolded proteins to an alternate protein export pathway. The NasE protein and the related NrtB and CmpB proteins of cyanobacteria contain unusual variants of the EAA loop sequence that defines membrane-intrinsic proteins of ABC transporters. To characterize nitrate and nitrite transport, we constructed in-frame nonpolar deletions of the chromosomal nasFED genes. Growth tests coupled with nitrate and nitrite uptake assays revealed that the nasFED genes are essential for nitrate transport and participate in nitrite transport as well. Interestingly, the ΔnasF strain exhibited leaky phenotypes, particularly at elevated nitrate concentrations, suggesting that the NasED proteins are not fully dependent on the NasF protein.

Seasonal and Water Column Trends of the Relative Role of Nitrate and Nitrite as *OH Sources in Surface Waters

2007 ◽  
Vol 97 (8) ◽  
pp. 699-711 ◽  
Author(s):  
Davide Vione ◽  
Claudio Minero ◽  
Valter Maurino ◽  
Ezio Pelizzetti
Keyword(s):  
Water Column ◽  
Surface Waters ◽  
Relative Role ◽  
Nitrate And Nitrite

scholarly journals The role of inorganic nitrate and nitrite in CVD

2017 ◽  
Vol 30 (2) ◽  
pp. 247-264 ◽  
Author(s):  
Jacklyn Jackson ◽  
Amanda J. Patterson ◽  
Lesley MacDonald-Wicks ◽  
Mark McEvoy
Keyword(s):  
Blood Pressure ◽  
Vegetable Consumption ◽  
The Body ◽  
Current Evidence ◽  
Nitrate Content ◽  
Platelet Activity ◽  
Cvd Risk ◽  
Inorganic Nitrate ◽  
Nitrate And Nitrite

AbstractCVD is the leading cause of death worldwide, a consequence of mostly poor lifestyle and dietary behaviours. Although whole fruit and vegetable consumption has been consistently shown to reduce CVD risk, the exact protective constituents of these foods are yet to be clearly identified. A recent and biologically plausible hypothesis supporting the cardioprotective effects of vegetables has been linked to their inorganic nitrate content. Approximately 60–80 % inorganic nitrate exposure in the human diet is contributed by vegetable consumption. Although inorganic nitrate is a relatively stable molecule, under specific conditions it can be metabolised in the body to produce NO via the newly discovered nitrate–nitrite–NO pathway. NO is a major signalling molecule in the human body, and has a key role in maintaining vascular tone, smooth muscle cell proliferation, platelet activity and inflammation. Currently, there is accumulating evidence demonstrating that inorganic nitrate can lead to lower blood pressure and improved vascular compliance in humans. The aim of this review is to present an informative, balanced and critical review of the current evidence investigating the role of inorganic nitrate and nitrite in the development, prevention and/or treatment of CVD. Although there is evidence supporting short-term inorganic nitrate intakes for reduced blood pressure, there is a severe lack of research examining the role of long-term nitrate intakes in the treatment and/or prevention of hard CVD outcomes, such as myocardial infarction and cardiovascular mortality. Epidemiological evidence is needed in this field to justify continued research efforts.

Inhibition of cystathionine-β-synthase activity during renal ischemia-reperfusion: role of pH and nitric oxide

2008 ◽  
Vol 295 (4) ◽  
pp. F912-F922 ◽  
Author(s):  
Gamika A. Prathapasinghe ◽  
Yaw L. Siow ◽  
Zhibin Xu ◽  
Karmin O
Keyword(s):  
Nitric Oxide ◽  
Ischemia Reperfusion ◽  
Left Kidney ◽  
Kidney Tissue ◽  
Sprague Dawley ◽  
Rate Limiting Step ◽  
Transsulfuration Pathway ◽  
Effects Of Ph ◽  
Nitrate And Nitrite

Our recent study (Prathapasinghe GA, Siow YL, O K. Am J Physiol Renal Physiol 292: F1354–F1363, 2007) indicates that homocysteine (Hcy) plays a detrimental role in ischemia-reperfusion-induced renal injury. Elevation of renal Hcy concentration during ischemia-reperfusion is attributed to reduced activity of cystathionine-β-synthase (CBS) that catalyzes the rate-limiting step in the transsulfuration pathway for the metabolism of the majority of Hcy in the kidney. However, the mechanisms of impaired CBS activity in the kidney are unknown. The aim of this study was to investigate the effects of pH and nitric oxide (NO) on the CBS activity in the kidney during ischemia-reperfusion. The left kidney of a Sprague-Dawley rat was subjected to ischemia-reperfusion. The CBS activity was significantly reduced in kidneys subjected to ischemia alone (15–60 min) or subjected to ischemia followed by reperfusion for 1–24 h. The pH was markedly reduced in kidneys upon ischemia. Injection of alkaline solution into the kidney partially restored the CBS activity during ischemia. Further analysis revealed that reduction of CBS activity during reperfusion was accompanied by an elevation of NO metabolites (nitrate and nitrite) in the kidney tissue. Injection of a NO scavenger, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO), restored the CBS activity in the kidneys subjected to ischemia-reperfusion. Treatment with PTIO could abolish ischemia-reperfusion-induced lipid peroxidation and prevent cell death in the kidney. These results suggested that metabolic acidosis during ischemia and accumulation of NO metabolites during reperfusion contributed, in part, to reduced CBS activity leading to an elevation of renal Hcy levels, which in turn, played a detrimental role in the kidney.

scholarly journals Dimethylated sulfur compounds in the Peruvian upwelling system

2021 ◽  
Author(s):  
Yanan Zhao ◽  
Dennis Booge ◽  
Christa A. Marandino ◽  
Cathleen Schlundt ◽  
Astrid Bracher ◽  
...  
Keyword(s):  
Surface Waters ◽  
Nitrogen Limitation ◽  
Trace Gas ◽  
Radical Scavengers ◽  
Upwelling System ◽  
Main Driver ◽  
Minimum Zone ◽  
Nitrate And Nitrite ◽  
Oxygen Minimum

Abstract. Our understanding of the biogeochemical cycling of the climate-relevant trace gas dimethylsulfide (DMS) in the Peruvian upwelling system is still limited. Here we present, oceanic and atmospheric DMS measurements which were made during two shipborne cruises in December 2012 (M91) and October 2015 (SO243) in the Peruvian upwelling region. Dimethylsulfoniopropionate (DMSP) and dimethylsulfoxide (DMSO) were also measured during M91. Relatively low DMS concentrations were measured in surface waters in October 2015 (1.9 ± 0.9 nmol L−1) and December 2012 (2.5 ± 1.9 nmol L−1). Nutrient availability appeared to be the main driver of the observed variability in the surface DMS distributions in the coastal areas. DMS, DMSP and DMSO showed maxima in the surface layer and no elevated concentrations associated with the oxygen minimum zone off Peru were measured. The possible role of DMS, DMSP and DMSO as radical scavengers (stimulated by nitrogen limitation) is supported by their negative correlations with N : P (sum of nitrate and nitrite: dissolved phosphate) ratios. Large variations in atmospheric DMS mole fractions were measured during M91 (144.6 ± 95.0 ppt) and SO243 (91.4 ± 55.8 ppt); however, the atmospheric mole fractions were generally low, and the sea-to-air flux density was primarily driven by seawater DMS. The Peruvian upwelling region was identified as a source of atmospheric DMS in December 2012 and October 2015, however, in comparison to the global monthly Lana climatology (mean: 6.2–9.8 μmol m−2 d−1 in October/December) (Lana et al., 2011), the Peru upwelling was not a hotspot of DMS emissions at either time (M91: 5.9 ± 5.3 μmol m−2 d−1; SO243: 3.8 ± 2.7 μmol m−2 d−1).

scholarly journals Salivary Nitrate, Nitrite and Nitrate Reductase Activity in Relation to Risk of Oral Cancer in Egypt

1998 ◽  
Vol 14 (2) ◽  
pp. 91-97 ◽  
Author(s):  
Alaa F. Badawi ◽  
Gehan Hosny ◽  
Mohamed El-Hadary ◽  
Mostafa H. Mostafa
Keyword(s):  
Oral Cancer ◽  
Nitrate Reductase ◽  
Odds Ratio ◽  
Nitrate Reductase Activity ◽  
Reductase Activity ◽  
Healthy Individuals ◽  
Oral Cancer Patients ◽  
Nitrate And Nitrite ◽  
Increased Activity

It has been suggested that nitrate and nitrite may play a role in the etiology of human oral cancer. We investigated whether salivary nitrate and nitrite and the activity of nitrate reductase (NRase) may affect the risk of oral cancer in Egypt, an area with high levels of environmental nitrosating agents. Levels of salivary nitrite (8.3 ± 1.0 μg/ml) and nitrate (44 ± 3.7 μg/ml) and activity of NRase (74 ± 10 nmol/ml/min) were significantly (P< 0.05) higher in oral cancer patients (n= 42) compared to control Egyptian healthy individuals (n= 40, nitrite = 5.3 ± 0.3 μg/ml, nitrate = 27 ± 1.2 μg/ml, and NRase activity = 46 ± 4 nmol/ml/min). The adjusted odds ratio (OR) and the 95% confidence intervals (C.I.) for risk of oral cancer, categorized by the levels of salivary nitrate and nitrite and NRase activity, showed a higher cancer risk associated with nitrite > 7.5 μg/ml (OR: 3.0, C.I.: 1.0–9.3), nitrite > 40 μg/ml (OR: 4.3, C.I.: 1.4–13.3) and NRase activity > 50 nmol/ml/min (OR: 2.9, C.I.: 1.1–7.4). Our findings suggest that increased consumption of dietary nitrate and nitrite is associated with elevated levels of salivary nitrite. Together with the increased activity of salivary NRase, these observations may explain, at least in part, the role of nitrate and nitrite in the development of oral cancer in individuals from an area with a high burden ofN-nitroso precursors.

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