TheAzospirillum brasilense rpoNgene is involved in nitrogen fixation, nitrate assimilation, ammonium uptake, and flagellar biosynthesis

1996 ◽  
Vol 42 (5) ◽  
pp. 467-478 ◽  
Author(s):  
Anne Milcamps ◽  
Anne Van Dommelen ◽  
John Stigter ◽  
Jos Vanderleyden ◽  
Frans J. de Bruijn
Keyword(s):  
Nitrogen Fixation ◽  
Azospirillum Brasilense ◽  
Nitrate Assimilation ◽  
Ammonium Assimilation ◽  
Gene Replacement ◽  
Ammonium Uptake ◽  
Significant Similarity ◽  
Sigma 54 ◽  
Azospirillum Brasilense Sp7

The rpoN (ntrA) gene (encoding sigma 54) of Azospirillum brasilense Sp7 was isolated by using conserved rpoN primers and the polymerase chain reaction, and its nucleotide sequence was determined. The deduced amino acid sequence of the RpoN protein was found to share a high degree of homology with other members of the sigma 54 family. Two additional open reading frames were found in the Azospirillum brasilense rpoN region, with significant similarity to equivalent regions surrounding the rpoN locus in other bacteria. An rpoN mutant of Azospirillum brasilense Sp7 was constructed by gene replacement and found to be defective in nitrogen fixation, nitrate assimilation, and ammonium uptake. Lack of ammonium uptake was also found in previously isolated Azospirillum brasilense ntrB and ntrC mutants, further supporting the role of the ntr system in this process. In addition, the rpoN mutant was found to be nonmotile, suggesting a role of RpoN in Azospirillum brasilense flagellar biosynthesis.Key words: Azospirillum brasilense, sigma factor, nitrogen fixation, ammonium assimilation, motility.

Role of a Fasciclin domain protein in photooxidative stress and flocculation in Azospirillum brasilense Sp7

2021 ◽  
pp. 103875
Author(s):  
Ashutosh Prakash Dubey ◽  
Parul Pandey ◽  
Shivangi Mishra ◽  
Parikshit Gupta ◽  
Anil Kumar Tripathi
Keyword(s):  
Azospirillum Brasilense ◽  
Photooxidative Stress ◽  
Azospirillum Brasilense Sp7 ◽  
Domain Protein

Over-expression of the rice OsAMT1-1 gene increases ammonium uptake and content, but impairs growth and development of plants under high ammonium nutrition

2006 ◽  
Vol 33 (2) ◽  
pp. 153 ◽  
Author(s):  
Mohammad S. Hoque ◽  
Josette Masle ◽  
Michael K. Udvardi ◽  
Peter R. Ryan ◽  
Narayana M. Upadhyaya
Keyword(s):  
Transgenic Plants ◽  
Ammonium Assimilation ◽  
Ammonium Transporter ◽  
Ammonium Uptake ◽  
Vegetative Stage ◽  
Over Expression ◽  
Transgenic Lines ◽  
Ammonium Nutrition ◽  
Maize Ubiquitin Promoter

A transgenic approach was undertaken to investigate the role of a rice ammonium transporter (OsAMT1-1) in ammonium uptake and consequent ammonium assimilation under different nitrogen regimes. Transgenic lines overexpressing OsAMT1-1 were produced by Agrobacterium-mediated transformation of two rice cultivars, Taipei 309 and Jarrah, with an OsAMT1-1 cDNA gene construct driven by the maize ubiquitin promoter. Transcript levels of OsAMT1-1 in both Taipei 309 and Jarrah transgenic lines correlated positively with transgene copy number. Shoot and root biomass of some transgenic lines decreased during seedling and early vegetative stage compared to the wild type, especially when grown under high (2 mm) ammonium nutrition. Transgenic plants, particularly those of cv. Jarrah recovered in the mid-vegetative stage under high ammonium nutrition. Roots of the transgenic plants showed increased ammonium uptake and ammonium content. We conclude that the decreased biomass of the transgenic lines at early stages of growth might be caused by the accumulation of ammonium in the roots owing to the inability of ammonium assimilation to match the greater ammonium uptake.

Regulation of nitrogen fixation in Azospirillum brasilense Sp7: Involvement of nifA, glnA and glnB gene products

1992 ◽  
Vol 100 (1-3) ◽  
pp. 113-119 ◽  
Author(s):  
Yao Yun Liang ◽  
Miklos Zamaroczy ◽  
Florence Arsene ◽  
Annick Paquelin ◽  
Claudine Elmerich
Keyword(s):  
Nitrogen Fixation ◽  
Azospirillum Brasilense ◽  
Gene Products ◽  
Azospirillum Brasilense Sp7

scholarly journals Phasin PhaP1 is involved in polyhydroxybutyrate granules morphology and in controlling early biopolymer accumulation in Azospirillum brasilense Sp7

AMB Express ◽  
2019 ◽  
Vol 9 (1) ◽  
Author(s):  
María de los Angeles Martínez-Martínez ◽  
Bertha González-Pedrajo ◽  
Georges Dreyfus ◽  
Lucía Soto-Urzúa ◽  
Luis Javier Martínez-Morales
Keyword(s):  
Azospirillum Brasilense ◽  
C:N Ratio ◽  
Growth Conditions ◽  
Low Oxygen ◽  
Rt Pcr ◽  
Transmission Electron ◽  
Azospirillum Brasilense Sp7 ◽  
Plant Growth Promoting ◽  
Growth Promoting

Abstract Phasins are amphiphilic proteins involved in the regulation of the number and size of polyhydroxybutyrate (PHB) granules. The plant growth promoting bacterium Azospirillum brasilense Sp7 accumulates high quantities of bioplastic PHB as carbon and energy source. By analyzing the genome, we identified six genes that code for proteins with a Phasin_2 domain. To understand the role of A. brasilense Sp7 PhaP1 (PhaP1Abs) on PHB synthesis, the phaP1 gene (AMK58_RS17065) was deleted. The morphology of the PHB granules was analyzed by transmission electron microscopy (TEM) and the PHB produced was quantified under three different C:N ratios in cultures subjected to null or low-oxygen transfer. The results showed that PhaP1Abs is involved in PHB granules morphology and in controlling early biopolymer accumulation. Using RT-PCR it was found that phasin genes, except phaP4, are transcribed in accordance with the C:N ratio used for the growth of A. brasilense. phaP1, phaP2 and phaP3 genes were able to respond to the growth conditions tested. This study reports the first analysis of a phasin protein in A. brasilense Sp7.

scholarly journals Involvement of glnB, glnZ, and glnD Genes in the Regulation of Poly-3-Hydroxybutyrate Biosynthesis by Ammonia in Azospirillum brasilense Sp7

2002 ◽  
Vol 68 (2) ◽  
pp. 985-988 ◽  
Author(s):  
Jun Sun ◽  
Anne Van Dommelen ◽  
Jan Van Impe ◽  
Jos Vanderleyden
Keyword(s):  
Growth Phase ◽  
Azospirillum Brasilense ◽  
Regulatory Genes ◽  
Wild Type ◽  
Active Growth ◽  
Phb Production ◽  
Azospirillum Brasilense Sp7

ABSTRACT The role of three key nitrogen regulatory genes, glnB (encoding the PII protein), glnZ (encoding the Pz protein), and glnD (encoding the GlnD protein), in regulation of poly-3-hydroxybutyrate (PHB) biosynthesis by ammonia in Azospirillum brasilense Sp7 was investigated. It was observed that glnB glnZ and glnD mutants produce substantially higher amounts of PHB than the wild type produces during the active growth phase. glnB and glnZ mutants have PHB production phenotypes similar to that of the wild type. Our results indicate that the PII-Pz system is apparently involved in nitrogen-dependent regulation of PHB biosynthesis in A. brasilense Sp7.

scholarly journals Role of NtcB in Activation of Nitrate Assimilation Genes in the Cyanobacterium Synechocystis sp. Strain PCC 6803

2001 ◽  
Vol 183 (20) ◽  
pp. 5840-5847 ◽  
Author(s):  
Makiko Aichi ◽  
Nobuyuki Takatani ◽  
Tatsuo Omata
Keyword(s):  
Nitrate Assimilation ◽  
Ammonium Assimilation ◽  
Dependent Manner ◽  
Wild Type ◽  
Transcriptional Enhancer ◽  
Genes Encoding ◽  
Different Strains ◽  
Pcc 7942 ◽  
Pcc 6803

ABSTRACT In Synechocystis sp. strain PCC 6803, the genes encoding the proteins involved in nitrate assimilation are organized into two transcription units,nrtABCD-narB and nirA, the expression of which was repressed by ammonium and induced by inhibition of ammonium assimilation, suggesting involvement of NtcA in the transcriptional regulation. Under inducing conditions, expression of the two transcription units was enhanced by nitrite, suggesting regulation by NtcB, the nitrite-responsive transcriptional enhancer we previously identified in Synechococcus sp. strain PCC 7942. The slr0395 gene, which encodes a protein 47% identical to Synechococcus NtcB, was identified as theSynechocystis ntcB gene, on the basis of the inability of an slr0395 mutant to rapidly accumulate the transcripts of the nitrate assimilation genes upon induction and to respond to nitrite. While Synechococcus NtcB strictly requires nitrite for its action, Synechocystis NtcB enhanced transcription significantly even in the absence of nitrite. Whereas the Synechococcus ntcB mutant expresses the nitrate assimilation genes to a significant level in an NtcA-dependent manner, the Synechocystis ntcB mutant showed only low-level expression of the nitrate assimilation genes, indicating that NtcA by itself cannot efficiently promote expression of these genes inSynechocystis. Activities of the nitrate assimilation enzymes in the Synechocystis ntcB mutant were consequently low, being 40 to 50% of the wild-type level, and the cells grew on nitrate at a rate approximately threefold lower than that of the wild-type strain. These results showed that the contribution of NtcB to the expression of nitrate assimilation capability varies considerably among different strains of cyanobacteria.

scholarly journals The Azospirillum brasilense Core Chemotaxis Proteins CheA1 and CheA4 Link Chemotaxis Signaling with Nitrogen Metabolism

mSystems ◽  
2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Elena E. Ganusova ◽  
Lam T. Vo ◽  
Paul E. Abraham ◽  
Lindsey O’Neal Yoder ◽  
Robert L. Hettich ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogen Metabolism ◽  
Azospirillum Brasilense ◽  
Regulatory Networks ◽  
Growth Promotion ◽  
Bacterial Chemotaxis ◽  
Nitrate Assimilation ◽  
Free Living ◽  
Content Type ◽  
Chemotaxis Proteins

ABSTRACT Bacterial chemotaxis affords motile bacteria the ability to navigate the environment to locate niches for growth and survival. At the molecular level, chemotaxis depends on chemoreceptor signaling arrays that interact with cytoplasmic proteins to control the direction of movement. In Azospirillum brasilense, chemotaxis is mediated by two distinct chemotaxis pathways: Che1 and Che4. Both Che1 and Che4 are critical in the A. brasilense free-living and plant-associated lifestyles. Here, we use whole-cell proteomics and metabolomics to characterize the role of chemotaxis in A. brasilense physiology. We found that mutants lacking CheA1 or CheA4 or both are affected in nonchemotaxis functions, including major changes in transcription, signaling transport, and cell metabolism. We identify specific effects of CheA1 and CheA4 on nitrogen metabolism, including nitrate assimilation and nitrogen fixation, that may depend, at least, on the transcriptional control of rpoN, which encodes RpoN, a global regulator of metabolism, including nitrogen. Consistent with proteomics, the abundance of several nitrogenous compounds (purines, pyrimidines, and amino acids) changed in the metabolomes of the chemotaxis mutants relative to the parental strain. Further, we uncover novel, and yet uncharacterized, layers of transcriptional and posttranscriptional control of nitrogen metabolism regulators. Together, our data reveal roles for CheA1 and CheA4 in linking chemotaxis and nitrogen metabolism, likely through control of global regulatory networks. IMPORTANCE Bacterial chemotaxis is widespread in bacteria, increasing competitiveness in diverse environments and mediating associations with eukaryotic hosts ranging from commensal to beneficial and pathogenic. In most bacteria, chemotaxis signaling is tightly linked to energy metabolism, with this coupling occurring through the sensory input of several energy-sensing chemoreceptors. Here, we show that in A. brasilense the chemotaxis proteins have key roles in modulating nitrogen metabolism, including nitrate assimilation and nitrogen fixation, through novel and yet unknown regulations. These results are significant given that A. brasilense is a model bacterium for plant growth promotion and free-living nitrogen fixation and is used as a bio-inoculant for cereal crops. Chemotaxis signaling in A. brasilense thus links locomotor behaviors to nitrogen metabolism, allowing cells to continuously and reciprocally adjust metabolism and chemotaxis signaling as they navigate gradients.

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