Modification of NO−3 metabolism in heterocysts of the N2-fixing cyanobacterium Anabaena 7120 (ATCC27893)

Rai, A

doi:10.1016/0378-1097(86)90299-5

Cited by 3 publications

(2 citation statements)

References 18 publications

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“…This is clearly the case whether ammonia is derived via N2 fixation in heterocysts or via processes such as NO? reduction (Rai & Bergman, 1986) or photorespiratory nitrogen cycling (Bergman, 1984) in vegetative cells. However, the liberation of ammonia by strain 4m3, treated with MSX, is more extensive than that by the parent strain, particularly in the presence of nitrate.…”

Section: Discussionmentioning

confidence: 99%

Characterization of Methylammonium/Ammonium Transport in Mutant Strains of Anabaena variabilis Resistant to Ammonium Analogues

et al. 1989

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A methylamine-resistant mutant strain (4m3) of Anabaena variabilis ATCC 2941 3 was capable of growth at pH 7.0, but not at pH 9.0, in the presence of concentrations of methylamine that totally inhibited growth of the parent strain. Strain 4m3 showed a marked reduction, at pH 7.0 but not at pH 9.0, in the initial rapid and slower second phases of uptake of [14C]methylamine and ammonia, when compared with the parent strain, The rate of inhibition of nitrogenase activity, on adding ammonia at pH 7.0, was lower in strain 4m3 than in the parent strain and was attributable to a defect in the CH,NH$/NH,' transport system. Evidence that the second slower phase of [ 14C]methylamine uptake is associated with metabolism via glutamine synthetase (GS) was obtained using mutant strains partially deficient in GS. Unlike these GSdeficient strains, strain 4m3 did not liberate ammonia extracellularly unless treated with t-methionine-DL-sulphoximine. Growth of strain 4m3 in medium containing 3 mMmethylamine resulted in a restoration of the first phase of [14C]methylamine uptake, at pH 7.0, but not of ammonia uptake. However, growth in the presence of 3 mM-ammonia did not enhance the uptake of either methylamine or ammonia. Strain 4m3 is apparently deficient in the active CH,NHS/NH: transport system, but has a CH,NHZ transport system which can be induced by growth in the presence of methylamine.

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Section: Discussionmentioning

confidence: 99%

Characterization of Methylammonium/Ammonium Transport in Mutant Strains of Anabaena variabilis Resistant to Ammonium Analogues

et al. 1989

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“…When given N 2 as sole nitrogen source, heterocystous cyanobacteria undergo profound morphological and physiological changes, culminating in the development of heterocysts [160, 206]. In addition to the appearance of nitrogenase activity, development of heterocysts from vegetative cells results in increased intracellular concentrations of glutamine synthetase and increased respiratory activity, but loss of Rubisco, nitrate reductase and photosynthetic O 2 evolution [131, 205, 207–209]. Often, but not always, the accessory photosynthetic phycobiliprotein pigments are lost during heterocyst differentiation.…”

Section: Nitrogenase and Metabolismmentioning

confidence: 99%

N2 Fixation by non-heterocystous cyanobacteria1

Bergman

Gallon

Rai

et al. 2006

FEMS Microbiology Reviews

165

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Many, though not all, non‐heterocystous cyanobacteria can fix N2. However, very few strains can fix N2 aerobically. Nevertheless, these organisms may make a substantial contribution to the global nitrogen cycle. In this general review, N2 fixation by laboratory cultures and natural populations of non‐heterocystous cyanobacteria is considered. The properties and subcellular location of nitrogenase in these organisms is described, as is the response of N2 fixation to environmental factors such as fixed nitrogen, O2 and the pattern of illumination. The integration of N2 fixation with other aspects of cell metabolism (in particular photosynthesis) is also discussed. Similarities and differences between different individual strains of non‐heterocystous cyanobacteria are highlighted.

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Correlation between nitrogenase and glutamine synthetase expression in the cyanobacterium Anabaena cylindrical

Renström‐Keliner

Amar

Bergman

1990

Physiologia Plantarum

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Distribution pattern and levels of nitrogenase (EC 1.7.99.2) and glutamine synthetase (GS, EC 6.3.1.2) were studied in N2‐, NO3− and NH4+ grown Anabaena cylindrica (CCAP 1403/2a) using immunogold electron microscopy. In N2‐ and NO3− grown cultures, heterocysts were formed and nitrogenase activity was present. The nitrogenase antigen appeared within the heterocysts only and showed an even distribution. The level of nitrogenase protein in the heterocysts was identical with both nitrogen sources. In NO3− grown cells the 30% reduction in the nitrogenase activity was due to a corresponding decrease in the heterocyst frequency and not to a repressed nitrogenase synthesis. In NH4− grown cells, the nitrogenase activity was almost zero and new heterocysts were formed to a very low extent. The heterocysts found showed practically no nitrogenase protein throughout the cytoplasm, although some label occurred at the periphery of the heterocyst. This demonstrates that heterocyst differentiation and nitrogenase expression are not necessarily correlated and that while NH4+ caused repression of both heterocyst and nitrogenase synthesis, NO3− caused inhibition of heterocyst differentiation only. The glutamine synthetase protein label was found throughout the vegetative cells and the heterocysts of all three cultures. The relative level of the GS antigen varied in the heterocysts depending on the nitrogen source, whereas the GS level was similar in all vegetative cells. In N2‐ and NO3+ grown cells, where nitrogenase was expressed, the GS level was ca 100% higher in the heterocysts compared to vegetative cells. In NH4+ grown cells, where nitrogenase was repressed, the GS level was similar in the two cell types. The enhanced level of GS expressed in heterocysts of N2 and NO3− grown cultures apparently is related to nitrogenase expression and has a role in assimilation of N2derived ammonia.

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Modification of NO−3 metabolism in heterocysts of the N2-fixing cyanobacterium Anabaena 7120 (ATCC27893)

Cited by 3 publications

References 18 publications

Characterization of Methylammonium/Ammonium Transport in Mutant Strains of Anabaena variabilis Resistant to Ammonium Analogues

Characterization of Methylammonium/Ammonium Transport in Mutant Strains of Anabaena variabilis Resistant to Ammonium Analogues

N2 Fixation by non-heterocystous cyanobacteria1

Correlation between nitrogenase and glutamine synthetase expression in the cyanobacterium Anabaena cylindrical

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