Evidence for an involvement of glutamine synthetase in regulation of nitrogenase activity in Rhodopseudomonas capsulata

1979 ◽  
Vol 122 (2) ◽  
pp. 213-218 ◽  
Author(s):  
P. Hillmer ◽  
K. Fahlbusch
Keyword(s):  
Glutamine Synthetase ◽  
Nitrogenase Activity ◽  
Rhodopseudomonas Capsulata

scholarly journals Regulation of nitrogenase A and R concentrations in Rhodopseudomonas capsulata by glutamine synthetase

1980 ◽  
Vol 187 (1) ◽  
pp. 273-276 ◽  
Author(s):  
D C Yoch
Keyword(s):  
Glutamine Synthetase ◽  
Nitrogenase Activity ◽  
Photosynthetic Bacterium ◽  
Rhodopseudomonas Capsulata ◽  
Wild Type ◽  
Sulphur Bacteria ◽  
Intracellular Concentrations ◽  
Methionine Sulphoximine ◽  
Negative Mutant

Nitrogen-starved purple non-sulphur bacteria have an active unregulated form of nitrogenase (nitrogenase A); however, the nitrogenase of a glutamine synthetase-negative mutant of Rhodopseudomonas capsulata, when nitrogen-starved, was predominantly inactive and required activation by Mn2+ and activating-factor protein. This regulatory form of nitrogenase has been called nitrogenase R. Treatment of wild-type cells (containing nitrogenase A) with methionine sulphoximine, an inhibitor of glutamine synthetase, converted the enzyme into nitrogenase R. Glutamine synthetase thus appears to control the intracellular concentrations of nitrogenase A and R and in this way regulates nitrogenase activity in the photosynthetic bacterium.

Regulation of Nitrogenase Activity in Rhodopseudomonas capsulata AD 2

1983 ◽  
Vol 38 (5-6) ◽  
pp. 436-438
Author(s):  
Kassem Alef
Keyword(s):  
Nitrogenase Activity ◽  
Rhodopseudomonas Capsulata ◽  
N Starvation

Regulation of nitrogenase activity in Rhodopseudomonas capsulata AD 2 differs in several respects from other Rhodospirillaceae: 1)Nitrogenase activity in this strain grown under severe N-starvation was fully derepressed, but in contrast to other Rhodospirillaceae, it was inhibited by ammonia in vivo. 2)Nitrogenase in extracts of glutamate grown cells was fully active and not further stimulated by Mn2+. 3)Treatment of N-starved or glutamate grown cells with ammonia before harvest did not cause inactivation of nitrogenase in vitro.

scholarly journals Glutamine synthetase and glutamate synthase activities in relation to nitrogen fixation in Lotus spp.

2000 ◽  
Vol 12 (3) ◽  
pp. 195-202 ◽  
Author(s):  
SUSANA GONNET ◽  
PEDRO DÍAZ
Keyword(s):  
Nitrogen Fixation ◽  
Amino Acid ◽  
Glutamine Synthetase ◽  
Nitrogenase Activity ◽  
Amino Acid Content ◽  
Glutamate Synthase ◽  
Dry Weight ◽  
Ammonia Assimilation ◽  
Fresh Weight ◽  
Mesorhizobium Loti

Lotus corniculatus, L. tenuis, L. pedunculatus, and L. subbiflorus inoculated with Mesorhizobium loti NZP2037 strain were grown in a growth chamber. The plants dry weight (DW), the nodule fresh weight (FW), the nitrogenase activity, the nodule glutamine synthetase (GS) and glutamate synthase (GOGAT) activities, as well as the leghemoglobin content and the amino acid in the stem were measured 28 days after inoculation. The highest DW of plants was measured in L. tenuis and the highest FW of nodules was measured in L. pedunculatus. Nitrogenase activity in L. tenuis, L. pedunculatus and L. subbiflorus was six fold the activity in L. corniculatus. Nodule GS and GOGAT activities did not follow this same pattern. L. tenuis had the highest values of GS and GOGAT activities in the nodule, and a high nitrogenase activity which is consistent with its high plant DW. The four species of Lotus were compared and no correlation between nitrogen fixation parameters and ammonia assimilation enzymes was found, but the GS/GOGAT ratio has a positive and significant correlation (r²=0.82**) with the amino acid content in stems.

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