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The Distinctive Regulation of Cyanobacterial Glutamine Synthetase

Helmholtz Centre for Environmental Research, Department of Solar Materials, Permoserstrasse 15, D-04318 Leipzig, Germany
Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, Américo Vespucio 49, E-41092 Seville, Spain
Author to whom correspondence should be addressed.
Received: 25 September 2018 / Revised: 23 October 2018 / Accepted: 25 October 2018 / Published: 27 October 2018
PDF [1559 KB, uploaded 27 October 2018]


Glutamine synthetase (GS) features prominently in bacterial nitrogen assimilation as it catalyzes the entry of bioavailable nitrogen in form of ammonium into cellular metabolism. The classic example, the comprehensively characterized GS of enterobacteria, is subject to exquisite regulation at multiple levels, among them gene expression regulation to control GS abundance, as well as feedback inhibition and covalent modifications to control enzyme activity. Intriguingly, the GS of the ecologically important clade of cyanobacteria features fundamentally different regulatory systems to those of most prokaryotes. These include the interaction with small proteins, the so-called inactivating factors (IFs) that inhibit GS linearly with their abundance. In addition to this protein interaction-based regulation of GS activity, cyanobacteria use alternative elements to control the synthesis of GS and IFs at the transcriptional level. Moreover, cyanobacteria evolved unique RNA-based regulatory mechanisms such as glutamine riboswitches to tightly tune IF abundance. In this review, we aim to outline the current knowledge on the distinctive features of the cyanobacterial GS encompassing the overall control of its activity, sensing the nitrogen status, transcriptional and post-transcriptional regulation, as well as strain-specific differences. View Full-Text
Keywords: nitrogen assimilation; cyanobacteria; glutamine synthetase inactivating factors; glutamine riboswitches; non-coding RNAs nitrogen assimilation; cyanobacteria; glutamine synthetase inactivating factors; glutamine riboswitches; non-coding RNAs

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Bolay, P.; Muro-Pastor, M.I.; Florencio, F.J.; Klähn, S. The Distinctive Regulation of Cyanobacterial Glutamine Synthetase. Life 2018, 8, 52.

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