Artículo
Regulation of glutamine synthetase activity in the unicellular cyanobacterium Synechocystis sp. strain PCC 6803 by the nitrogen source: Effect of ammonium
Autor/es | Mérida Berlanga, Ángel
Candau Chacón, Pedro Florencio Bellido, Francisco Javier |
Departamento | Universidad de Sevilla. Departamento de Bioquímica Vegetal y Biología Molecular |
Fecha de publicación | 1991 |
Fecha de depósito | 2017-07-27 |
Publicado en |
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Resumen | Glutamine synthetase activity from Synechocystis sp. strain PCC 6803 is regulated as a function of the nitrogen source available in the medium. Addition of 0.25 mM NH4Cl to nitrate-grown cells promotes a clear short-term ... Glutamine synthetase activity from Synechocystis sp. strain PCC 6803 is regulated as a function of the nitrogen source available in the medium. Addition of 0.25 mM NH4Cl to nitrate-grown cells promotes a clear short-term inactivation of glutamine synthetase, whose enzyme activity decreases to 5 to 10% of the initial value in 25 min. The intracellular levels of glutamine, determined under various conditions, taken together with the results obtained with azaserine (an inhibitor of transamidases), rule out the possibility that glutamine per se is responsible for glutamine synthetase inactivation. Nitrogen starvation attenuates the ammonium-mediated glutamine synthetase inactivation, indicating that glutamine synthetase regulation is modulated through the internal balance between carbon-nitrogen compounds and carbon compounds. The parallelism observed between the glutamine synthetase activity and the internal concentration of α-ketoglutarate suggests that this metabolite could play a role as a positive effector of glutamine synthetase activity in Synechocystis sp. Despite the similarities of this physiological system to that described for enterobacteria, the lack of in vivo 32P labeling of glutamine synthetase during the inactivation process excludes the existence of an adenylylation-deadenylylation system in this cyanobacterium. |
Agencias financiadoras | Dirección General de Investigación Científica y Técnica (DGICYT). España |
Identificador del proyecto | PB 88-0020 |
Cita | Mérida Berlanga, Á., Candau Chacón, P. y Florencio Bellido, F.J. (1991). Regulation of glutamine synthetase activity in the unicellular cyanobacterium Synechocystis sp. strain PCC 6803 by the nitrogen source: Effect of ammonium. Journal of Bacteriology, 173 (13), 4095-4100. |
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