Nitrate metabolism in the cyanobacterium Anabaena cycadeae: Regulation of nitrate uptake and reductase by ammonia |
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| Authors: | Suvendra N Bagchi Upendra N Rai Amar N Rai Hriday N Singh |
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| Institution: | School of Life Sciences, Univ. of Hyderabad, Central University P.O., Hyderabad-500 134, India. |
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| Abstract: | Nitrogen regulation of nitrate uptake and nitrate reductase (EC 1.7.99.4) was studied in the cyanobacterium Anabaena cycadeae Reinke and its glutamine auxotroph. Development of the nitrate uptake system preceded, and was independent of, the development of the nitrate reductase system. The levels of both systems were several-fold higher in the glutamine auxotroph lacking glutamine synthetase (EC 6.3.1.2) than in the wild type strain having normal glutamine synthetase activity. The nitrate uptake system was found to be NH4-repressible and the nitrate reductase system NO3?-inducible. NH4+ was the initial repressor signal for the uptake process which was involved in the control of the NO3?inducible reductase system. |
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| Keywords: | Glutamine auxotroph glutamine synthetase |
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