Nitrogen Starvation Acclimation in Synechococcus elongatus: Redox-Control and the Role of Nitrate Reduction as an Electron Sink
Nitrogen starvation acclimation in non-diazotrophic cyanobacteria is characterized by a process termed chlorosis, where the light harvesting pigments are degraded and the cells gradually tune down photosynthetic and metabolic activities. The chlorosis response is governed by a complex and poorly und...
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MDPI AG
2015-03-01
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| Series: | Life |
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| Online Access: | http://www.mdpi.com/2075-1729/5/1/888 |
| _version_ | 1798041875229179904 |
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| author | Alexander Klotz Edgar Reinhold Sofía Doello Karl Forchhammer |
| author_facet | Alexander Klotz Edgar Reinhold Sofía Doello Karl Forchhammer |
| author_sort | Alexander Klotz |
| collection | DOAJ |
| description | Nitrogen starvation acclimation in non-diazotrophic cyanobacteria is characterized by a process termed chlorosis, where the light harvesting pigments are degraded and the cells gradually tune down photosynthetic and metabolic activities. The chlorosis response is governed by a complex and poorly understood regulatory network, which converges at the expression of the nblA gene, the triggering factor for phycobiliprotein degradation. This study established a method that allows uncoupling metabolic and redox-signals involved in nitrogen-starvation acclimation. Inhibition of glutamine synthetase (GS) by a precise dosage of l-methionine-sulfoximine (MSX) mimics the metabolic situation of nitrogen starvation. Addition of nitrate to such MSX-inhibited cells eliminates the associated redox-stress by enabling electron flow towards nitrate/nitrite reduction and thereby, prevents the induction of nblA expression and the associated chlorosis response. This study demonstrates that nitrogen starvation is perceived not only through metabolic signals, but requires a redox signal indicating over-reduction of PSI-reduced electron acceptors. It further establishes a cryptic role of nitrate/nitrite reductases as electron sinks to balance conditions of over-reduction. |
| first_indexed | 2024-04-11T22:27:39Z |
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| id | doaj.art-9f26c7137c424b1fa1620970583b832c |
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| issn | 2075-1729 |
| language | English |
| last_indexed | 2024-04-11T22:27:39Z |
| publishDate | 2015-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Life |
| spelling | doaj.art-9f26c7137c424b1fa1620970583b832c2022-12-22T03:59:36ZengMDPI AGLife2075-17292015-03-015188890410.3390/life5010888life5010888Nitrogen Starvation Acclimation in Synechococcus elongatus: Redox-Control and the Role of Nitrate Reduction as an Electron SinkAlexander Klotz0Edgar Reinhold1Sofía Doello2Karl Forchhammer3Interfakultäres Institut für Mikrobiologie und Infektionsmedizin der Eberhard-Karls-Universität Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, GermanyInterfakultäres Institut für Mikrobiologie und Infektionsmedizin der Eberhard-Karls-Universität Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, GermanyInterfakultäres Institut für Mikrobiologie und Infektionsmedizin der Eberhard-Karls-Universität Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, GermanyInterfakultäres Institut für Mikrobiologie und Infektionsmedizin der Eberhard-Karls-Universität Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, GermanyNitrogen starvation acclimation in non-diazotrophic cyanobacteria is characterized by a process termed chlorosis, where the light harvesting pigments are degraded and the cells gradually tune down photosynthetic and metabolic activities. The chlorosis response is governed by a complex and poorly understood regulatory network, which converges at the expression of the nblA gene, the triggering factor for phycobiliprotein degradation. This study established a method that allows uncoupling metabolic and redox-signals involved in nitrogen-starvation acclimation. Inhibition of glutamine synthetase (GS) by a precise dosage of l-methionine-sulfoximine (MSX) mimics the metabolic situation of nitrogen starvation. Addition of nitrate to such MSX-inhibited cells eliminates the associated redox-stress by enabling electron flow towards nitrate/nitrite reduction and thereby, prevents the induction of nblA expression and the associated chlorosis response. This study demonstrates that nitrogen starvation is perceived not only through metabolic signals, but requires a redox signal indicating over-reduction of PSI-reduced electron acceptors. It further establishes a cryptic role of nitrate/nitrite reductases as electron sinks to balance conditions of over-reduction.http://www.mdpi.com/2075-1729/5/1/888Synechococcus elongatus PCC 7942nblAglnBNtcAnitrogen starvation responsel-methionine-sulfoximineglutamine synthetase |
| spellingShingle | Alexander Klotz Edgar Reinhold Sofía Doello Karl Forchhammer Nitrogen Starvation Acclimation in Synechococcus elongatus: Redox-Control and the Role of Nitrate Reduction as an Electron Sink Life Synechococcus elongatus PCC 7942 nblA glnB NtcA nitrogen starvation response l-methionine-sulfoximine glutamine synthetase |
| title | Nitrogen Starvation Acclimation in Synechococcus elongatus: Redox-Control and the Role of Nitrate Reduction as an Electron Sink |
| title_full | Nitrogen Starvation Acclimation in Synechococcus elongatus: Redox-Control and the Role of Nitrate Reduction as an Electron Sink |
| title_fullStr | Nitrogen Starvation Acclimation in Synechococcus elongatus: Redox-Control and the Role of Nitrate Reduction as an Electron Sink |
| title_full_unstemmed | Nitrogen Starvation Acclimation in Synechococcus elongatus: Redox-Control and the Role of Nitrate Reduction as an Electron Sink |
| title_short | Nitrogen Starvation Acclimation in Synechococcus elongatus: Redox-Control and the Role of Nitrate Reduction as an Electron Sink |
| title_sort | nitrogen starvation acclimation in synechococcus elongatus redox control and the role of nitrate reduction as an electron sink |
| topic | Synechococcus elongatus PCC 7942 nblA glnB NtcA nitrogen starvation response l-methionine-sulfoximine glutamine synthetase |
| url | http://www.mdpi.com/2075-1729/5/1/888 |
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