scholarly journals Enhanced Nitrogen Fixation in a Rhizobium etli ntrC Mutant That Overproduces the Bradyrhizobium japonicum Symbiotic Terminal Oxidasecbb3

1999 ◽  
Vol 65 (5) ◽  
pp. 2015-2019 ◽  
Author(s):  
Mario Soberón ◽  
Oswaldo López ◽  
Claudia Morera ◽  
Maria de Lourdes Girard ◽  
Maria Luisa Tabche ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Bradyrhizobium Japonicum ◽  
Wild Type Strain ◽  
Terminal Oxidase ◽  
Rhizobium Etli ◽  
Transcriptional Activator Protein ◽  
Molecular Masses ◽  
Nitrogenase Activities ◽  
Production Pattern

ABSTRACT The ntrC gene codes for a transcriptional activator protein that modulates gene expression in response to nitrogen. The cytochrome production pattern of a Rhizobium etli ntrCmutant (CFN2012) was studied. CO difference spectral analysis of membranes showed that CFN2012 produced a terminal oxidase similar to the symbiotic terminal oxidase of bacteroids in free-living cells under aerobic conditions, with a characteristic trough at 553 nm. CFN2012 produced two c-type cytochromes with molecular masses of 27 and 32 kDa, in contrast with the wild-type strain, which produced only a 32-kDa c-type cytochrome. The expression levels of theR. etli fixNOQP operon, which codes for terminal oxidasecbb 3, were not affected by the ntrCmutation. However, the production levels of the two c-type cytochromes (27 and 32 kDa) were enhanced at least eightfold when theBradyrhizobium japonicum fixNOQP operon was expressed in CFN2012 from the nptII promoter (pMSfixc), suggesting that these proteins are subunits FixO (27 kDa) and FixP (32 kDa) of cbb 3 and that CFN2012/pMSfixc overproduced this terminal oxidase. CFN2012/pMSfixc showed a significant increase in its symbiotic performance as judged by the determination of nitrogenase activities of plants inoculated with this strain, suggesting that the overproduction of cbb 3 terminal oxidase correlates with an enhancement in symbiotic nitrogen fixation.

scholarly journals Novel Reiterated Fnr-Type Proteins Control the Production of the Symbiotic Terminal Oxidase cbb3 in Rhizobium etli CFN42

2007 ◽  
Vol 20 (10) ◽  
pp. 1241-1249 ◽  
Author(s):  
Manuel J. Granados-Baeza ◽  
Nicolás Gómez-Hernández ◽  
Yolanda Mora ◽  
María J. Delgado ◽  
David Romero ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Oxygen Affinity ◽  
Structural Similarity ◽  
Transcriptional Regulators ◽  
Terminal Oxidase ◽  
Nitrogen Fixing ◽  
Rhizobium Etli ◽  
High Oxygen Affinity ◽  
Key Genes

Symbiotic nitrogen-fixing bacteria express a terminal oxidase with a high oxygen affinity, the cbb3-type oxidase encoded by the fixNOQP operon. Previously, we have shown that, in Rhizobium etli CFN42, the repeated fixNOQP operons (fixNOQPd and fixNOQPf) have a differential role in nitrogen fixation. Only the fixNOQPd operon is required for the establishment of an effective symbiosis; microaerobic induction of this operon is under the control of at least three transcriptional regulators, FixKf, FnrNd, and FnrNchr, belonging to the Crp/Fnr family. In this work, we describe two novel Crp/Fnr-type transcriptional regulators (StoRd and StoRf, symbiotic terminal oxidase regulators) that play differential roles in the control of key genes for nitrogen fixation. Mutations either in stoRd or stoRf enhance the microaerobic expression of both fixNOQP reiterations, increasing also the synthesis of the cbb3-type oxidase in nodules. Despite their structural similarity, a differential role of these genes was also revealed, since a mutation in stoRd but not in stoRf enhanced both the expression of fixKf and the nitrogen-fixing capacity of R. etli CFN42.

scholarly journals Transcriptomic and Proteomic Analyses Reveal the Diversity of Venom Components from the Vaejovid Scorpion Serradigitus gertschi

Toxins ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 359 ◽  
Author(s):  
Maria Romero-Gutiérrez ◽  
Carlos Santibáñez-López ◽  
Juana Jiménez-Vargas ◽  
Cesar Batista ◽  
Ernesto Ortiz ◽  
...  
Keyword(s):  
Serine Proteases ◽  
De Novo ◽  
Sequence Similarity ◽  
Scorpion Venom ◽  
Secretory Proteins ◽  
Host Defense Peptides ◽  
The Family ◽  
Pathogenesis Related ◽  
Molecular Masses

To understand the diversity of scorpion venom, RNA from venomous glands from a sawfinger scorpion, Serradigitus gertschi, of the family Vaejovidae, was extracted and used for transcriptomic analysis. A total of 84,835 transcripts were assembled after Illumina sequencing. From those, 119 transcripts were annotated and found to putatively code for peptides or proteins that share sequence similarities with the previously reported venom components of other species. In accordance with sequence similarity, the transcripts were classified as potentially coding for 37 ion channel toxins; 17 host defense peptides; 28 enzymes, including phospholipases, hyaluronidases, metalloproteases, and serine proteases; nine protease inhibitor-like peptides; 10 peptides of the cysteine-rich secretory proteins, antigen 5, and pathogenesis-related 1 protein superfamily; seven La1-like peptides; and 11 sequences classified as “other venom components”. A mass fingerprint performed by mass spectrometry identified 204 components with molecular masses varying from 444.26 Da to 12,432.80 Da, plus several higher molecular weight proteins whose precise masses were not determined. The LC-MS/MS analysis of a tryptic digestion of the soluble venom resulted in the de novo determination of 16,840 peptide sequences, 24 of which matched sequences predicted from the translated transcriptome. The database presented here increases our general knowledge of the biodiversity of venom components from neglected non-buthid scorpions.

Bradyrhizobium japonicum mutants defective in root-nodule bacteroid development and nitrogen fixation

1986 ◽  
Vol 144 (4) ◽  
pp. 355-366 ◽  
Author(s):  
B. Regensburger ◽  
L. Meyer ◽  
M. Filser ◽  
J. Weber ◽  
D. Studer ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Bradyrhizobium Japonicum ◽  
Root Nodule

scholarly journals Potential of Phototrophic Purple Nonsulfur Bacteria to Fix Nitrogen in Rice Fields

2021 ◽  
Vol 10 (1) ◽  
pp. 28
Author(s):  
Isamu Maeda
Keyword(s):  
Nitrogen Fixation ◽  
Regulatory Networks ◽  
Nitrogenase Activity ◽  
Field Studies ◽  
Rice Fields ◽  
Purple Nonsulfur Bacteria ◽  
Available Nitrogen ◽  
Nitrogenase Activities ◽  
Plant Available Nitrogen ◽  
Biological Nitrogen

Biological nitrogen fixation catalyzed by Mo-nitrogenase of symbiotic diazotrophs has attracted interest because its potential to supply plant-available nitrogen offers an alternative way of using chemical fertilizers for sustainable agriculture. Phototrophic purple nonsulfur bacteria (PNSB) diazotrophically grow under light anaerobic conditions and can be isolated from photic and microaerobic zones of rice fields. Therefore, PNSB as asymbiotic diazotrophs contribute to nitrogen fixation in rice fields. An attempt to measure nitrogen in the oxidized surface layer of paddy soil estimates that approximately 6–8 kg N/ha/year might be accumulated by phototrophic microorganisms. Species of PNSB possess one of or both alternative nitrogenases, V-nitrogenase and Fe-nitrogenase, which are found in asymbiotic diazotrophs, in addition to Mo-nitrogenase. The regulatory networks control nitrogenase activity in response to ammonium, molecular oxygen, and light irradiation. Laboratory and field studies have revealed effectiveness of PNSB inoculation to rice cultures on increases of nitrogen gain, plant growth, and/or grain yield. In this review, properties of the nitrogenase isozymes and regulation of nitrogenase activities in PNSB are described, and research challenges and potential of PNSB inoculation to rice cultures are discussed from a viewpoint of their applications as nitrogen biofertilizer.

scholarly journals Nodulation and Development of Soybean Submitted to Inoculation With Bradyrhizobium japonicum and Phosphorus Doses

2018 ◽  
Vol 10 (12) ◽  
pp. 321 ◽  
Author(s):  
Erica Chaves ◽  
Rubson da Costa Leite ◽  
Thalita Rodrigues Silva ◽  
Thayny Alves Viana ◽  
Tatiane de Sousa Cruz ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Experimental Design ◽  
Bradyrhizobium Japonicum ◽  
Phosphate Fertilizer ◽  
Dry Mass ◽  
Root Number ◽  
Phosphate Fertilization ◽  
Soybean Plants ◽  
Biological Nitrogen ◽  
Plant Dry Mass

Among the several factors that may influence nodulation and the efficiency of biological nitrogen fixation for soybean plants, nutrient availability is among the most important. This study aimed to evaluate the inoculation with Bradyrhizobium japonicum and doses of phosphorus on the development of soybean in a Vertisol, in Tocantins. The experimental design was completely randomized in a 4 × 2 factorial scheme, with four replications. Four doses of phosphate fertilization (0, 100, 200, and 300 kg ha-1 P2O5) were studied, combined with two inoculation treatments with Bradyrhizobium japonicum (inoculated and not inoculated). The following variables were evaluated: plant height, stem diameter, nodules per plant, dry mass of nodules, dry mass of plant, dry mass of root, number of pods and number of grains per pod. Under greenhouse conditions and soil with good availability of phosphorus, there is no influence of the doses on the inoculation with Bradyrhizobium japonicum. Soils with good availability of phosphorus have low response to the application of phosphate fertilizer.

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