Further Studies on the Induction of Nitrate Reductase by Arginine in the Filamentous Cyanobacterium Oscillatoria chalybea

In an earlier publication we reported on the role of arginine for the development of nitrate reductase activity in cells of the filamentous cyanobacterium Oscillatoria chalybea (Bednarz and Schmid, Z. Naturforsch. 46c, 591 (1991)). In the present paper we present further evidence that arginine is the natural inducer for nitrate reductase activity. Thus, we show that the induction is regulated by transcription, probably related to the apoprotein or the molybdenumcofactor. We also examined the influence of arginine on nitrate reductase activity in the filamentous cyanobacterium Anabaena PCC7120. In contrast to Oscillatoria chalybea this cyanobacterium forms heterocysts and shows nitrogen fixation activity. Like in Oscillatoria chalybea nitrate reductase activity in Anabaena PCC7120 is stimulated in the presence of arginine as the sole nitrogen source. However, this stimulation is limited to an early growth stage. Subsequently, nitrogen fixation activity appears and nitrate reductase activity decreases.

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Induction of Nitrate Reductase Activity by Arginine in the Filamentous Cyanobacterium Oscillatoria chalybea

Zeitschrift für Naturforschung C ◽

10.1515/znc-1991-7-815 ◽

1991 ◽

Vol 46 (7-8) ◽

pp. 591-596 ◽

Cited By ~ 4

Author(s):

J. Bednarz ◽

G. H. Schmid

Keyword(s):

Nitrate Reductase ◽

Nitrogen Source ◽

Nitrate Reduction ◽

Nitrate Reductase Activity ◽

Reductase Activity ◽

Maximal Activity ◽

Substrate Affinity ◽

Filamentous Cyanobacterium ◽

Oscillatoria Chalybea ◽

Exogenous Nitrogen

Abstract In Oscillatoria chalybea, as in other cyanobacteria, nitrate reduction depends directly on photosynthetic activity. Hence, nitrate reduction occurs only in the light and appears inhibited when photosynthesis is inhibited by the herbicide DCMU . Growth of Oscillatoria cells is possible on a variety of exogenous nitrogen sources in the medium and appears largely independent on the type of nitrogen source. However, if citrulline is the exogenous nitrogen source or if no exogenous nitrogen source is given in the medium, growth appears almost fully inhibited. Nitrate reductase activity measured in French-press particles of nitrate-grown cells is dependent on the age of the culture with maximum nitrate reductase activity being reached on the 5th day. Thereafter activity decreases steeply to less than 20% of the maximal activity within 10 days. Besides the growth stage it is the type of exogenous nitrogen source used in the medium which is important for the development of nitrate reductase activity. It appears that in the presence of nitrate, nitrite and arginine, nitrate reductase activity is induced whereas in the presence of ammonia or amino acids like alanine nitrate reductase activity is not induced, as already reported in the literature. Nitrate reductase is also induced if arginine and ammonia are simultaneously offered as exogenous nitrogen source. Arginine metabolism in Oscillatoria cells is characterized by the fact that thylakoid preparations of Oscillatoria catalyze the trans formation of arginine to give ornithine and ammonium. The arginine-metabolizing enzyme differs from the usual arginine-induced arginase. The enzyme seems to be constitutive, not manganese-dependent, exhibiting an approximately 5 times higher substrate affinity to arginine than the known arginase. In the present paper we propose that in Oscillatoria it is arginine which induces the synthesis of nitrate reductase.

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Phenotypic reversion of nitrogenase in pleiotropic mutants of Rhizobium meliloti

Canadian Journal of Microbiology ◽

10.1139/m79-048 ◽

1979 ◽

Vol 25 (3) ◽

pp. 298-301 ◽

Cited By ~ 3

Author(s):

Ilona Barabás ◽

Tibor Sik

Keyword(s):

Amino Acids ◽

Nitrogen Fixation ◽

Nitrate Reductase ◽

Nitrate Reductase Activity ◽

Symbiotic Nitrogen Fixation ◽

Rhizobium Meliloti ◽

Nitrogenase Activity ◽

Reductase Activity ◽

Amino Acid Utilization ◽

Phenotypic Reversion

In two out of three pleiotropic mutants of Rhizobium meliloti, defective in nitrate reductase induced by amino acid utilization in vegetative bacteria and in symbiotic nitrogen fixation, nitrogenase activity could be restored completely by purines and partially by the amino acids L-glutamate, L-aspartate, L-glutamine, and L-asparagine. The compounds restoring effectiveness in nitrogen fixation did not restore nitrate reductase activity in vegetative bacteria. The restoration of effectiveness supports our earlier conclusion that the mutation is not in the structural gene for a suggested common subunit of nitrogenase and nitrate reductase.

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Nitrate modification of photosynthesis and photoassimilate export in young nodulated soybean plants

Canadian Journal of Botany ◽

10.1139/b82-323 ◽

1982 ◽

Vol 60 (12) ◽

pp. 2665-2670 ◽

Cited By ~ 12

Author(s):

D. J. Ursino ◽

D. M. Hunter ◽

R. D. Laing ◽

J. L. S. Keighley

Keyword(s):

Nitrogen Fixation ◽

Nitrate Reductase ◽

Nutrient Solution ◽

Nitrate Reductase Activity ◽

Reductase Activity ◽

Nodule Development ◽

Nitrate Availability ◽

Data Support ◽

Nutrient Fertilization ◽

Soybean Plants

Soybean plants (cv. Harosoy 63) inoculated with rhizobia were germinated from seed and beginning on day 7 after planting were subjected to one of four patterns of nutrient fertilization. One group received a nutrient solution containing 5 mM nitrate, a second group received nitrate-free nutrient solution, and two other groups received nitrate-containing solution either from days 7 to 13 or from days 14 to 20. On day 21 rates of leaf photosynthetic CO2 uptake and nitrate reductase activity were measured, as well as the capacities of the leaf to export recent photosynthate and of the nodules to reduce acetylene. The data support the hypothesis that sufficient nitrate availability in the leaves of young soybean plants can modify both photosynthetic CO2 uptake and light-mediated photoassimilate export to an extent that nodule development and the capacity for nitrogen fixation are reduced.

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Nitrate reductase activities of rhizobia and the correlation between nitrate reduction and nitrogen fixation

Canadian Journal of Microbiology ◽

10.1139/m79-181 ◽

1979 ◽

Vol 25 (10) ◽

pp. 1169-1174 ◽

Cited By ~ 33

Author(s):

James R. Manhart ◽

Peter P. Wong

Keyword(s):

Nitrogen Fixation ◽

Nitrate Reductase ◽

Nitrate Reduction ◽

Nitrate Reductase Activity ◽

Reductase Activity ◽

Root Nodules ◽

Sole Source ◽

Rhizobium Japonicum ◽

Rhizobium Trifolii ◽

Rhizobium Species

All species of Rhizobium except R. lupini had nitrate reductase activity. Only R. lupini was incapable of growth with nitrate as the sole source of nitrogen. However, the conditions necessary for the induction of nitrate reductase varied among species of Rhizobium. Rhizobium japonicum and some Rhizobium species of the cowpea strains expressed nitrate reductase activities both in the root nodules of appropriate leguminous hosts and when grown in the presence of nitrate. Rhizobium trifolii, R. phaseoli, and R. legnminosarum did not express nitrate reductase activities in the root nodules, but they did express them when grown in the presence of nitrate. In bacteroids of R. japonicum and some strains of cowpea Rhizobium, high N2 fixation activities were accompanied by high nitrate reductase activities. In bacteroids of R. trifolii, R. leguminosarum, and R. phaseoli, high N2 fixation activities were not accompanied by high nitrate reductase activities.

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