Aspects of Hydrogen Metabolism in Nitrogen-Fixing Legumes and Other Plant-Microbe Associations

Eisbrenner, G.; Evans, Harold J.

doi:10.1146/annurev.pp.34.060183.000541

Cited by 119 publications

(68 citation statements)

References 100 publications

(105 reference statements)

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“…The bacteroids produce nitrogenase for the reduction of N2 to ammonia. An inefficient property of the nitrogenase-catalyzed reaction is the reduction of protons to H2, which utilizes ATP (4,18). The efficiency of the symbiosis is improved with uptake hydrogenase (Hup) activity in the bacteroids, because the oxidation of H2 stimulates ATP production (5).…”

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confidence: 99%

“…Enhanced efficiency of symbiotic N2 fixation by H2 oxidation has been reported to increase soybean yield (6). Although H2 oxidation improves symbiotic N2 fixation, few strains of B. japonicum express Hup activity (4,18). Investigations of Hup activity in B. japonicum have been made predominantly with strains USDA 122 and USDA 110 or with antibioticresistant clones of these two strains.…”

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confidence: 99%

“…Rates of H2 oxidation with sodium glutamate and NH4Cl were 40. 4 (1). Therefore, the H2-oxidizing cultures were tested for ex planta nitrogenase activity because of the reported coordinated regulation of nitrogenase and Hup activities (7).…”

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Expression of uptake hydrogenase and hydrogen oxidation during heterotrophic growth of Bradyrhizobium japonicum

Berkum

1987

J Bacteriol

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Strains 1-110 ARS, SR, USDA 136, USDA 137, and AK13 lc of Bradyrhizobium japonicum induced Hup activity when growing heterotrophically in medium with carbon substrate and NH4Cl in the presence of 2% H2 and 2% 02. Hup activity was induced during heterotrophic growth in the presence of carbon substrates, which were assimilated during the time of H2 oxidation. Strains 1-110 ARS and SR grown heterotrophically or chemoautotrophically for 3 days had similar rates of H2 oxidation. Similar rates of Hup activity were also observed when cell suspensions were induced for 24 h in heterotrophic or chemoautotrophic growth medium with 1% 02, 10% H2, and 5% CO2 in N2. These results are contrary to the reported repression of Hup activity by carbon substrates in B. japonicum. Bradyrhizobial Hup activity during heterotrophic growth was limited by H2 and 02 and repressed by aerobic conditions, and CO2 addition had no effect. Nitrogenase and ribulosebisphosphate carboxylase activities were not detected in H2-oxidizing cultures of B. japonicum during heterotrophic growth. Immunoblot analysis of cell extracts with antibodies prepared against the 65-kilodalton subunit of uptake hydrogenase indicated that Hup protein synthesis was induced by H2 and repressed under aerobic conditions.

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Expression of uptake hydrogenase and hydrogen oxidation during heterotrophic growth of Bradyrhizobium japonicum

Berkum

1987

J Bacteriol

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“…Since this was an unexpected finding, physiological parameters were studied, common to species without active hydrogenase and which differed from those containing hydrogenase activity. Comparative physiological investigations on factors involved in regulation of hydrogenase in heterocystous cyanobacteria are needed to broaden, our knowledge on hydrogen metabolism, which still is poorly understood, although some details have been reported during the last decade (7,9). ' ( 15).…”

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Physiological Factors Determining Hydrogenase Activity in Nitrogen-Fixing Heterocystous Cyanobacteria

Chen¹,

Almon²,

Böger³

1989

Plant Physiol.

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Four species of nitrogen-fixing heterocystous cyanobacteria were compared with respect to induction of hydrogenase activity. Two of the strains contained phycoerythrin and built up high levels of carbohydrate storage material when grown in batch culture under nitrogen-fixing conditions and continuous illumination. These strains did not exhibit hydrogenase activity. Lack of activity in the phycoerythrin-containing species was determined by cell-free assays measuring both hydrogen-evolving and hydrogen-uptake activities. Apparentiy, expression of hydrogenase is negatively correlated with the carbohydrate pool present and concurrent respiration. Furthermore, there is an apparent relationship between the presence of phycoerythrin, carbohydrate accumulation, and the absence of hydrogenase activity.Many nitrogen-fixing cyanobacteria contain an uptake hydrogenase, which consumes the hydrogen which is produced by nitrogenase during reduction of dinitrogen. Hydrogenase activity varies during the course of cultivation and is influenced by external factors such as light intensity (18) or availability of nickel (1, 6). Comparing hydrogenase activity in four strains of heterocystous cyanobacteria (three Anabaena strains and a Hapalosiphon species), we found that two of these did not exhibit any hydrogenase activity throughout the entire cultivation period. Since this was an unexpected finding, physiological parameters were studied, common to species without active hydrogenase and which differed from those containing hydrogenase activity. Comparative physiological investigations on factors involved in regulation of hydrogenase in heterocystous cyanobacteria are needed to broaden, our knowledge on hydrogen metabolism, which still is poorly understood, although some details have been reported during the last decade (7, 9).

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“…Many N2-reducing bacteria, and specifically some Rhizobium organisms, have evolved a separate Hup2 system that oxidizes the H2 to water (12). Potential benefits of the Hup+ phenotype discussed by Dixon (I 1) include (a) increased utilization of02 which might protect the 02-sensitive nitrogenase system, (b) removal of H2 which inhibits nitrogenase, and (c) coupling of H2 oxidation to ATP synthesis.…”

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Sodium Stimulation of Uptake Hydrogenase Activity In Symbiotic Rhizobium

Kapulnik¹,

Phillips²

1986

Plant Physiol.

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Initial observations showed a 100% increase in Hruptake (Hup) activity of Rhizobium legumixosarum strain 3855 in pea root nodules (Pisum sativum L. cv Alaska) on plants growing in a baked clay substrate relative to those growing in vermiculite, and an investigation of nutrient factors responsible for the phenomenon was initiated. Signifiantly greater Hup activity was first measured in the clay-rown plants 24 days after germination, and higher activity was maintained relative to the vermiculite treatment until experiments were terminated at day 32. The increase in Hup activity was associated with a decrease in H2 evolution for plants with comparable rates of acetylene reduction. Analyses of the cLay showed that it contained more Na (29 versus 9 milligrams per kilogram) and less K' (6 versus 74 milligrams per kilogram) than the vermiculite. Analyses of plants, however, showed a lare increase in Na' concentration of clay-grown plants with a much smaller reduction in K concentration. In tests with the same organisms in a hydroponic system with controlled pH, 40 millimolar NaCI increased Hup activity more than 100% over plants grown in solutions lacking NaCI. Plants with increased Hup activity, however, did not have greater net carbon or total nitrogen assimilation. KCI treatments from 5 to 80 millimolar produced slight increased in Hup activity at 10 millimolar KC] and tests with other salts in the hydroponic system indicated that only Na strongly promoted Hup activity. Treating vermiculite with 50 millimolar NaCI increased Na concentration in pea plant tissue and greatly promoted Hup activity of root nodules in a manner analogous to the original observation with the clay rooting medium. A wider generality of the phenomenon was suggested by demonstrating that exogenous Na increased Hup activity of other R. kguminosarum strains and promoted Hup activity of R. meliloti strain B300 in alfalfa (Medicago sativa L.).The nitrogenase enzyme complex of procaryotes catalyzes a concurrent reduction of N2 and protons to produce NH3 and H2.Even under 5 M,4Pa of N2, the system continues to allocate at

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Aspects of Hydrogen Metabolism in Nitrogen-Fixing Legumes and Other Plant-Microbe Associations

Cited by 119 publications

References 100 publications

Expression of uptake hydrogenase and hydrogen oxidation during heterotrophic growth of Bradyrhizobium japonicum

Expression of uptake hydrogenase and hydrogen oxidation during heterotrophic growth of Bradyrhizobium japonicum

Physiological Factors Determining Hydrogenase Activity in Nitrogen-Fixing Heterocystous Cyanobacteria

Sodium Stimulation of Uptake Hydrogenase Activity In Symbiotic Rhizobium

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