scholarly journals Characterization of the Oxygen-Responsive NreABC Regulon of Staphylococcus aureus

2008 ◽  
Vol 190 (23) ◽  
pp. 7847-7858 ◽  
Author(s):  
Steffen Schlag ◽  
Stephan Fuchs ◽  
Christiane Nerz ◽  
Rosmarie Gaupp ◽  
Susanne Engelmann ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Transcriptional Activation ◽  
Nitrite Reduction ◽  
Anaerobic Growth ◽  
Regulation System ◽  
Anoxic Environments ◽  
Severe Impairment ◽  
Specific Regulation ◽  
Nitrate And Nitrite

ABSTRACT Here, we investigate the functionality of the oxygen-responsive nitrogen regulation system NreABC in the human pathogen Staphylococcus aureus and evaluate its role in anaerobic gene regulation and virulence factor expression. Deletion of nreABC resulted in severe impairment of dissimilatory nitrate and nitrite reduction and led to a small-colony phenotype in the presence of nitrate during anaerobic growth. For characterization of the NreABC regulon, comparative DNA microarray and proteomic analyses between the wild type and nreABC mutant were performed under anoxic conditions in the absence and presence of nitrate. A reduced expression of virulence factors was not observed in the mutant. However, both the transcription of genes involved in nitrate and nitrite reduction and the accumulation of corresponding proteins were highly decreased in the nreABC mutant, which was unable to utilize nitrate as a respiratory oxidant and, hence, was forced to use fermentative pathways. These data were corroborated by the quantification of the extracellular metabolites lactate and acetate. Using an Escherichia coli-compatible two-plasmid system, the activation of the promoters of the nitrate and nitrite reductase operons and of the putative nitrate/nitrite transporter gene narK by NreBC was confirmed. Overall, our data indicate that NreABC is very likely a specific regulation system that is essential for the transcriptional activation of genes involved in dissimilatory reduction and transport of nitrate and nitrite. The study underscores the importance of NreABC as a fitness factor for S. aureus in anoxic environments.

Nitrate and nitrite reduction by ferrous iron minerals in polluted groundwater: Isotopic characterization of batch experiments

2020 ◽  
Vol 548 ◽  
pp. 119691
Author(s):  
Rosanna Margalef-Marti ◽  
Raúl Carrey ◽  
José Antonio Benito ◽  
Vicenç Marti ◽  
Albert Soler ◽  
...  
Keyword(s):  
Ferrous Iron ◽  
Nitrite Reduction ◽  
Batch Experiments ◽  
Iron Minerals ◽  
Isotopic Characterization ◽  
Nitrate And Nitrite

A composite biochemical system for bacterial nitrate and nitrite assimilation as exemplified by Paracoccus denitrificans

2011 ◽  
Vol 435 (3) ◽  
pp. 743-753 ◽  
Author(s):  
Andrew J. Gates ◽  
Victor M. Luque-Almagro ◽  
Alan D. Goddard ◽  
Stuart J. Ferguson ◽  
M. Dolores Roldán ◽  
...  
Keyword(s):  
Nitrate Reductase ◽  
Nitrogen Source ◽  
Nitrite Reductase ◽  
Paracoccus Denitrificans ◽  
Gene Clusters ◽  
Anion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Nitrite Reduction ◽  
Anaerobic Growth ◽  
Nitrate And Nitrite

The denitrifying bacterium Paracoccus denitrificans can grow aerobically or anaerobically using nitrate or nitrite as the sole nitrogen source. The biochemical pathway responsible is expressed from a gene cluster comprising a nitrate/nitrite transporter (NasA), nitrite transporter (NasH), nitrite reductase (NasB), ferredoxin (NasG) and nitrate reductase (NasC). NasB and NasG are essential for growth with nitrate or nitrite as the nitrogen source. NADH serves as the electron donor for nitrate and nitrite reduction, but only NasB has a NADH-oxidizing domain. Nitrate and nitrite reductase activities show the same Km for NADH and can be separated by anion-exchange chromatography, but only fractions containing NasB retain the ability to oxidize NADH. This implies that NasG mediates electron flux from the NADH-oxidizing site in NasB to the sites of nitrate and nitrite reduction in NasC and NasB respectively. Delivery of extracellular nitrate to NasBGC is mediated by NasA, but both NasA and NasH contribute to nitrite uptake. The roles of NasA and NasC can be substituted during anaerobic growth by the biochemically distinct membrane-bound respiratory nitrate reductase (Nar), demonstrating functional overlap. nasG is highly conserved in nitrate/nitrite assimilation gene clusters, which is consistent with a key role for the NasG ferredoxin, as part of a phylogenetically widespread composite nitrate and nitrite reductase system.

scholarly journals A haloarchaeal ferredoxin electron donor that plays an essential role in nitrate assimilation

2011 ◽  
Vol 39 (6) ◽  
pp. 1844-1848 ◽  
Author(s):  
Basilio Zafrilla ◽  
Rosa María Martínez-Espinosa ◽  
María José Bonete ◽  
Julea N. Butt ◽  
David J. Richardson ◽  
...  
Keyword(s):  
Essential Role ◽  
Inorganic Nitrogen ◽  
Nitrate Assimilation ◽  
Spectroscopic Characterization ◽  
Redox Properties ◽  
Nitrite Reduction ◽  
Plant Type ◽  
Uv Visible ◽  
Nitrate And Nitrite

In the absence of ammonium, many organisms, including the halophilic archaeon Haloferax volcanii DS2 (DM3757), may assimilate inorganic nitrogen from nitrate or nitrite, using a ferredoxin-dependent assimilatory NO3−/NO2− reductase pathway. The small acidic ferredoxin Hv-Fd plays an essential role in the electron transfer cascade required for assimilatory nitrate and nitrite reduction by the cytoplasmic NarB- and NirA-type reductases respectively. UV–visible absorbance and EPR spectroscopic characterization of purified Hv-Fd demonstrate that this protein binds a single [2Fe–2S] cluster, and potentiometric titration reveals that the cluster shares similar redox properties with those present in plant-type ferredoxins.

Physiological Characterization of Cyanophora paradoxa, a Flagellate Containing Cyanelles in Endosymbiosis

1978 ◽  
Vol 33 (11-12) ◽  
pp. 981-987 ◽  
Author(s):  
Hermann Bothe ◽  
Liliane Floener
Keyword(s):  
Green Algae ◽  
Generation Time ◽  
Culture Conditions ◽  
Nitrite Reduction ◽  
Cyanophora Paradoxa ◽  
Blue Green Algae ◽  
Carbon And Nitrogen ◽  
Physiological Characterization ◽  
Nitrate And Nitrite

Culture conditions are described under which Cyanophora paradoxa grows with a generation time of less than two days. The organism is an obligate photoautotrophic flagellate unable to degrade exogenous carbohydrates via respiration. It does not synthesize nitrogenase but can form a hydrogenase with similar properties as in blue-green algae. The photosynthetic O2-evolution pro­ceeds with essentially the same rate as in green or blue-green algae. Besides CO2, p-benzochinon, nitrate and nitrite also stimulate the photosynthetic O2-evolution. Nitrite reduction is strictly light- dependent where the stoicheiometry between nitrite-disappearance and photosynthetic O2-evolution is 1:1.5. It is concluded that the cyanelles supply the eucaryotic host both with carbon and nitrogen compounds.

Phylogeny Characterization of Seb Gene Encoding Enterotoxins in Staphylococcus aureus Isolated from Raw Milk and Cheese

2019 ◽  
Vol 9 (o3) ◽  
Author(s):  
Fatima N. Aziz ◽  
Laith Abdul Hassan Mohammed-Jawad
Keyword(s):  
Staphylococcus Aureus ◽  
Food Poisoning ◽  
Raw Milk ◽  
Staphylococcal Enterotoxin B ◽  
Human Pathogen ◽  
Conventional Pcr ◽  
Biochemical Tests ◽  
Specific Primers ◽  
Gene Encoding

Food poisoning due to the bacteria is a big global problem in economically and human's health. This problem refers to an illness which is due to infection or the toxin exists in nature and the food that use. Milk is considered a nutritious food because it contains proteins and vitamins. The aim of this study is to detect and phylogeny characterization of staphylococcal enterotoxin B gene (Seb). A total of 200 milk and cheese samples were screened. One hundred ten isolates of Staphylococcus aureus pre-confirmed using selective and differential media with biochemical tests. Genomic DNA was extracted from the isolates and the SEB gene detects using conventional PCR with specific primers. Three staphylococcus aureus isolates were found to be positive for Seb gene using PCR and confirmed by sequencing. Sequence homology showed variety range of identity starting from (100% to 38%). Phylogenetic tree analyses show that samples (6 and 5) are correlated with S. epidermidis. This study discovered that isolates (A6-RLQ and A5-RLQ) are significantly clustered in a group with non- human pathogen Staphylococcus agnetis.

Sign in / Sign up

Export Citation Format

Share Document