scholarly journals Role of Asparagine in the Photorespiratory Nitrogen Metabolism of Pea Leaves

1985 ◽  
Vol 78 (2) ◽  
pp. 334-337 ◽  
Author(s):  
Trung Chanh Ta ◽  
Kenneth W. Joy ◽  
Robert J. Ireland
Keyword(s):  
Nitrogen Metabolism

scholarly journals Metabolic Switching of Mycobacterium tuberculosis during Hypoxia Is Controlled by the Virulence Regulator PhoP

2020 ◽  
Vol 202 (7) ◽  
Author(s):  
Prabhat Ranjan Singh ◽  
Anil Kumar Vijjamarri ◽  
Dibyendu Sarkar
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Nitrogen Metabolism ◽  
Electron Acceptor ◽  
Latent Infection ◽  
Critical Role ◽  
Hypoxic Stress ◽  
Content Type ◽  
Metabolic Switching ◽  
Virulence Regulator

ABSTRACT Mycobacterium tuberculosis retains the ability to establish an asymptomatic latent infection. A fundamental question in mycobacterial physiology is to understand the mechanisms involved in hypoxic stress, a critical player in persistence. Here, we show that the virulence regulator PhoP responds to hypoxia, the dormancy signal, and effectively integrates hypoxia with nitrogen metabolism. We also provide evidence to demonstrate that both under nitrogen limiting conditions and during hypoxia, phoP locus controls key genes involved in nitrogen metabolism. Consistently, under hypoxia a ΔphoP strain shows growth attenuation even with surplus nitrogen, the alternate electron acceptor, and complementation of the mutant restores bacterial growth. Together, our observations provide new biological insights into the role of PhoP in integrating nitrogen metabolism with hypoxia by the assistance of the hypoxia regulator DosR. The results have significant implications on the mechanism of intracellular survival and growth of the tubercle bacilli under a hypoxic environment within the phagosome. IMPORTANCE M. tuberculosis retains the unique ability to establish an asymptomatic latent infection. To understand the mechanisms involved in hypoxic stress which play a critical role in persistence, we show that the virulence regulator PhoP is linked to hypoxia, the dormancy signal. In keeping with this, phoP was shown to play a major role in M. tuberculosis growth under hypoxia even in the presence of surplus nitrogen, the alternate electron acceptor. Our results showing regulation of hypoxia-responsive genes provide new biological insights into role of the virulence regulator in metabolic switching by sensing hypoxia and integrating nitrogen metabolism with hypoxia by the assistance of the hypoxia regulator DosR.

Re-print of “Intestinal luminal nitrogen metabolism: Role of the gut microbiota and consequences for the host”

2013 ◽  
Vol 69 (1) ◽  
pp. 114-126 ◽  
Author(s):  
Anne-Marie Davila ◽  
François Blachier ◽  
Martin Gotteland ◽  
Mireille Andriamihaja ◽  
Pierre-Henri Benetti ◽  
...  
Keyword(s):  
Gut Microbiota ◽  
Nitrogen Metabolism

scholarly journals Role of Ureolytic Activity in Bacillus cereus Nitrogen Metabolism and Acid Survival

2008 ◽  
Vol 74 (8) ◽  
pp. 2370-2378 ◽  
Author(s):  
Maarten Mols ◽  
Tjakko Abee
Keyword(s):  
Bacillus Cereus ◽  
Nitrogen Source ◽  
Nitrogen Metabolism ◽  
Acid Stress ◽  
Main Role ◽  
Strain Atcc ◽  
Acid Shock ◽  
Acidic Conditions ◽  
The Impact

ABSTRACT The presence and activities of urease genes were investigated in 49 clinical, food, and environmental Bacillus cereus isolates. Ten strains were shown to have urease genes, with eight of these strains showing growth on urea as the sole nitrogen source. Two of the urease-positive strains, including the sequenced strain ATCC 10987, could not use urea for growth, despite their capacities to produce active urease. These observations can be explained by the inability of the two strains to use ammonium as a nitrogen source. The impact of urea hydrolysis on acid stress resistance was subsequently assessed among the ureolytic B. cereus strains. However, none of the strains displayed increased fitness under acidic conditions or showed enhanced acid shock survival in the presence of urea. Expression analysis of urease genes in B. cereus ATCC 10987 revealed a low level of expression of these genes and a lack of pH-, nitrogen-, urea-, oxygen-, and growth phase-dependent modulation of mRNA transcription. This is in agreement with the low urease activity observed in strain ATCC 10987 and the other nine strains tested. Although a role for B. cereus ureolytic activity in acid survival cannot be excluded, its main role appears to be in nitrogen metabolism, where ammonium may be provided to the cells in nitrogen-limited, urea-containing environments.

scholarly journals The Role of Pseudomonas in Heterotrophic Nitrification: A Case Study on Shrimp Ponds (Litopenaeus vannamei) in Soc Trang Province

2019 ◽  
Vol 7 (6) ◽  
pp. 155
Author(s):  
Thanh Trung Tran ◽  
Nathan J. Bott ◽  
Nhan Dai Lam ◽  
Nam Trung Nguyen ◽  
Oanh Hoang Thi Dang ◽  
...  
Keyword(s):  
Nitrogen Metabolism ◽  
Litopenaeus Vannamei ◽  
Heterotrophic Nitrification ◽  
Rrna Gene ◽  
Shrimp Ponds ◽  
Total Ammonia ◽  
Gene Data ◽  
Predictive Functions

Based on a total of 6,295,650 sequences from the V3 and V4 regions (16S ribosomal RNA), the composition of the microorganism communities in the water of three Litopenaeus vannamei (Decapoda, Whiteleg shrimp; Soc Trang, Vietnam) ponds were identified. Pseudomonas (10–20.29%), Methylophilus (13.26–24.28%), and Flavobacterium (2.6–19.29%) were the most abundant genera. The total ammonia (TAN) concentration (p = 0.025) and temperature (p = 0.015) were significantly correlated with the relative abundance of Pseudomonas in two bacterial communities (ST1, ST4), whereas the predictive functions of microorganism communities based on 16S rRNA gene data was estimated using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUST), which showed that nitrogen metabolism was significantly negatively correlated (p = 0.049) with TAN concentration. The abundance of Pseudomonas and nitrogen metabolism increased with a decrease in TAN concentration. The correlation between TAN concentration and the abundance of Pseudomonas was followed by the isolation, and heterotrophic nitrifying performance analysis was used to confirm our findings. Six Pseudomonas strains capable of heterotrophic nitrification were isolated from the three water samples and showed a complete reduction of 100 mg/L NH4Cl during a 96-h cultivation. These results indicate the potential of applying Pseudomonas in shrimp ponds for water treatment.

scholarly journals Nitrogen Metabolism in Sinorhizobium meliloti–Alfalfa Symbiosis: Dissecting the Role of GlnD and PII Proteins

2012 ◽  
Vol 25 (3) ◽  
pp. 355-362 ◽  
Author(s):  
Svetlana N. Yurgel ◽  
Jennifer Rice ◽  
Michael L. Kahn
Keyword(s):  
Nitrogen Metabolism ◽  
Sinorhizobium Meliloti ◽  
Protein A ◽  
Normal Operation ◽  
Triple Mutant ◽  
Free Living ◽  
Cleavage Enzyme ◽  
Pii Proteins ◽  
Nitrogen Exchange

To contribute nitrogen for plant growth and establish an effective symbiosis with alfalfa, Sinorhizobium meliloti Rm1021 needs normal operation of the GlnD protein, a bifunctional uridylyltransferase/uridylyl-cleavage enzyme that measures cellular nitrogen status and initiates a nitrogen stress response (NSR). However, the only two known targets of GlnD modification in Rm1021, the PII proteins GlnB and GlnK, are not necessary for effectiveness. We introduced a Tyr→Phe variant of GlnB, which cannot be uridylylated, into a glnBglnK background to approximate the expected state in a glnD-sm2 mutant, and this strain was effective. These results suggested that unmodified PII does not inhibit effectiveness. We also generated a glnBglnK-glnD triple mutant and used this and other mutants to dissect the role of these proteins in regulating the free-living NSR and nitrogen metabolism in symbiosis. The glnD-sm2 mutation was dominant to the glnBglnK mutations in symbiosis but recessive in some free-living phenotypes. The data show that the GlnD protein has a role in free-living growth and in symbiotic nitrogen exchange that does not depend on the PII proteins, suggesting that S. meliloti GlnD can communicate with the cell by alternate mechanisms.

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