Dataset Information

Levels of Periplasmic Nitrate Reductase during Denitrification are Lower in Bradyrhizobium japonicum than in Bradyrhizobium diazoefficiens.

ABSTRACT: Soybean plants host endosymbiotic dinitrogen (N2)-fixing bacteria from the genus Bradyrhizobium. Under oxygen-limiting conditions, Bradyrhizobium diazoefficiens and Bradyrhizobium japonicum perform denitrification by sequentially reducing nitrate (NO3-) to nitrous oxide (N2O) or N2. The anaerobic reduction of NO3- to N2O was previously shown to be lower in B. japonicum than in B. diazoefficiens due to impaired periplasmic nitrate reductase (Nap) activity in B. japonicum. We herein demonstrated that impaired Nap activity in B. japonicum was due to low Nap protein levels, which may be related to a decline in the production of FixP and FixO proteins by the cbb3-type oxidase.

SUBMITTER: Siqueira AF

PROVIDER: S-EPMC7511789 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Levels of Periplasmic Nitrate Reductase during Denitrification are Lower in Bradyrhizobium japonicum than in Bradyrhizobium diazoefficiens.

Siqueira Arthur Fernandes AF Sugawara Masayuki M Arashida Haruka H Minamisawa Kiwamu K Sánchez Cristina C

Microbes and environments 20200101 3

Soybean plants host endosymbiotic dinitrogen (N2)-fixing bacteria from the genus Bradyrhizobium. Under oxygen-limiting conditions, Bradyrhizobium diazoefficiens and Bradyrhizobium japonicum perform denitrification by sequentially reducing nitrate (NO3-) to nitrous oxide (N2O) or N2. The anaerobic reduction of NO3- to N2O was previously shown to be lower in B. japonicum than in B. diazoefficiens due to impaire ...[more]

PMID: 32554940

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Project description:Sulfur (S)-containing molecules play an important role in symbiotic nitrogen fixation and are critical components of nitrogenase and other iron-S proteins. S deficiency inhibits symbiotic nitrogen fixation by rhizobia. However, despite its importance, little is known about the sources of S that rhizobia utilize during symbiosis. We previously showed that Bradyrhizobium diazoefficiens USDA110T can assimilate both inorganic and organic S and that genes involved in organic S utilization are expressed during symbiosis. Here, we show that a B. diazoefficiens USDA110T mutant with a sulfonate monooxygenase (ssuD) insertion is defective in nitrogen fixation. Microscopy analyses revealed that the ΔssuD mutant was defective in root hair infection and that ΔssuD mutant bacteroids showed degradation compared to the wild-type strain. Moreover, the ΔssuD mutant was significantly more sensitive to hydrogen peroxide-mediated oxidative stress than the wild-type strain. Taken together, these results show that the ability of rhizobia to utilize organic S plays an important role in symbiotic nitrogen fixation. Since nodules have been reported to be an important source of reduced S used during symbiosis and nitrogen fixation, further research will be needed to determine the mechanisms involved in the regulation of S assimilation by rhizobia.IMPORTANCE Rhizobia form symbiotic associations with legumes that lead to the formation of nitrogen-fixing nodules. Sulfur-containing molecules play a crucial role in nitrogen fixation; thus, the rhizobia inside nodules require large amounts of sulfur. Rhizobia can assimilate both inorganic (sulfate) and organic (sulfonates) sources of sulfur. However, very little is known about rhizobial sulfur metabolism during symbiosis. In this report, we show that sulfonate utilization by Bradyrhizobium diazoefficiens is important for symbiotic nitrogen fixation in both soybean and cowpea. The symbiotic defect is probably due to increased sensitivity to oxidative stress from sulfur deficiency in the mutant strain defective for sulfonate utilization. The results of this study can be extended to other rhizobium-legume symbioses, as sulfonate utilization genes are widespread in these bacteria.

Dataset Information

Levels of Periplasmic Nitrate Reductase during Denitrification are Lower in Bradyrhizobium japonicum than in Bradyrhizobium diazoefficiens.

Publications

Levels of Periplasmic Nitrate Reductase during Denitrification are Lower in Bradyrhizobium japonicum than in Bradyrhizobium diazoefficiens.

Similar Datasets

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