A Plethora of Terminal Oxidases and Their Biogenesis Factors in<i>Bradyrhizobium japonicum</i>

Youard, Zeb A.; Abicht, Helge K.; Mohorko, Elisabeth; Serventi, Fabio; Rigozzi, Eugenia; Ledermann, Raphael; Fischer, Hans‐Martin; Glockshuber, Rudi; Hennecke, Hauke

doi:10.1002/9781119053095.ch29

Cited by 8 publications

(6 citation statements)

References 87 publications

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“…However, still many features of rhizobial respiration are unknown. The genome of B. japonicum encodes as many as eight different terminal oxidases for respiration in oxic conditions (Youard et al, 2015). Thus, even though respiration is crucial for efficiency, no definite answers to whether respiratory activity or nitrogenase function limits efficiency of N 2 fixation have so far been identified in this complex system.…”

Section: Energy Supply To Nitrogenase: the O 2 Paradoxmentioning

confidence: 99%

Effectiveness of nitrogen fixation in rhizobia

Lindström

Mousavi

2019

Microbial Biotechnology

289

157

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Summary Biological nitrogen fixation in rhizobia occurs primarily in root or stem nodules and is induced by the bacteria present in legume plants. This symbiotic process has fascinated researchers for over a century, and the positive effects of legumes on soils and their food and feed value have been recognized for thousands of years. Symbiotic nitrogen fixation uses solar energy to reduce the inert N 2 gas to ammonia at normal temperature and pressure, and is thus today, especially, important for sustainable food production. Increased productivity through improved effectiveness of the process is seen as a major research and development goal. The interaction between rhizobia and their legume hosts has thus been dissected at agronomic, plant physiological, microbiological and molecular levels to produce ample information about processes involved, but identification of major bottlenecks regarding efficiency of nitrogen fixation has proven to be complex. We review processes and results that contributed to the current understanding of this fascinating system, with focus on effectiveness of nitrogen fixation in rhizobia.

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Section: Energy Supply To Nitrogenase: the O 2 Paradoxmentioning

confidence: 99%

Effectiveness of nitrogen fixation in rhizobia

Lindström

Mousavi

2019

Microbial Biotechnology

289

157

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“…To circumvent this apparent paradox, where oxygen is needed to energize nitrogen fixation and nitrogenase is sensitive to oxygen, rhizobia possess high-affinity terminal oxidases that allow respiration at low oxygen concentrations. Rhizobia can usually express a complex set of different respiratory oxygen reductases, reflecting their diverse lifestyles (127)(128)(129)(130). Biochemical and genetic data show that a cytochrome c oxidase, encoded by fixNOQP, is a high affinity cbb 3 -type oxidase responsible for respiration under microaerobic conditions in rhizobia.…”

Section: Adaptations To Microaerobic Conditionsmentioning

confidence: 99%

How Rhizobia Adapt to the Nodule Environment

2021

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Rhizobia are a phylogenetically diverse group of soil bacteria that engage in mutualistic interactions with legume plants. Although specifics of the symbioses differ between strains and plants, all symbioses ultimately result in the formation of specialized root nodule organs which host the nitrogen-fixing microsymbionts called bacteroids. Inside nodules, bacteroids encounter unique conditions that necessitate global reprogramming of physiological processes and rerouting of their metabolism. Decades of research have addressed these questions using genetics, omics approaches, and more recently computational modelling. Here we discuss the common adaptations of rhizobia to the nodule environment that define the core principles of bacteroid functioning. All bacteroids are growth-arrested and perform energy-intensive nitrogen fixation fueled by plant-provided C4-dicarboxylates at nanomolar oxygen levels. At the same time, bacteroids are subject to host control and sanctioning that ultimately determine their fitness and have fundamental importance for the evolution of a stable mutualistic relationship.

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“…Notably, however, cycA and coxA mutants retained partial chemolithoautotrophic activity with thiosulfate, which suggests that alternative routes of electron transfer might exist in these mutants. Notably, B. diazoefficiens possesses two additional cytochrome oxidases and four additional ubiquinol oxidases that, collectively, might be responsible for the residual chemolithotrophic activity [ 9 , 31 ]. Whether one of these six oxidases plays an equally prominent role as the aa 3 -type oxidase in thiosulfate oxidation is difficult to predict, as we have no knowledge about the biochemical components (quinols, cytochromes) to which the enzymatic Sox complex of B. diazoefficiens delivers its electrons first.…”

Section: Resultsmentioning

confidence: 99%

Requirements for Efficient Thiosulfate Oxidation in Bradyrhizobium diazoefficiens

Masuda

Hennecke

Fischer

2017

Genes

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One of the many disparate lifestyles of Bradyrhizobium diazoefficiens is chemolithotrophic growth with thiosulfate as an electron donor for respiration. The employed carbon source may be CO2 (autotrophy) or an organic compound such as succinate (mixotrophy). Here, we discovered three new facets of this capacity: (i) When thiosulfate and succinate were consumed concomitantly in conditions of mixotrophy, even a high molar excess of succinate did not exert efficient catabolite repression over the use of thiosulfate. (ii) Using appropriate cytochrome mutants, we found that electrons derived from thiosulfate during chemolithoautotrophic growth are preferentially channeled via cytochrome c550 to the aa3-type heme-copper cytochrome oxidase. (iii) Three genetic regulators were identified to act at least partially in the expression control of genes for chemolithoautotrophic thiosulfate oxidation: RegR and CbbR as activators, and SoxR as a repressor.

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A Plethora of Terminal Oxidases and Their Biogenesis Factors inBradyrhizobium japonicum

Cited by 8 publications

References 87 publications

Effectiveness of nitrogen fixation in rhizobia

Effectiveness of nitrogen fixation in rhizobia

How Rhizobia Adapt to the Nodule Environment

Requirements for Efficient Thiosulfate Oxidation in Bradyrhizobium diazoefficiens

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