Site-2 Protease Slr1821 Regulates Carbon/Nitrogen Homeostasis during Ammonium Stress Acclimation in Cyanobacterium Synechocystis sp. PCC 6803

Lin, Sihao; Li, Shiliang; Ouyang, Tong; Li, Zhuoshi

doi:10.3390/ijms24076606

Cited by 3 publications

(1 citation statement)

References 75 publications

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“…2B). These data agree with the results of a recent transcriptome analysis in which the ncr1071 transcript was upregulated ~threefold during acclimation to ammonium stress [33], indicating that the C/N balance is pivotal for the transcription of nirP1.…”

Section: Two Transcription Factors Are Involved In the Regulation Of ...supporting

confidence: 91%

Nitrite excretion by cyanobacteria is controlled by the small protein NirP1

Hess,

Kraus,

Spät

et al. 2023

Preprint

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When the supply of inorganic carbon is limiting, photosynthetic cyanobacteria excrete nitrite, a toxic intermediate in the ammonia assimilation pathway from nitrate. While it has been hypothesized that the excreted nitrite represents excess nitrogen that could not be further assimilated due to the missing carbon, the underlying molecular mechanism has remained enigmatic. Here, we characterized a hitherto unannotated gene with homologs in the genomes of 485 different cyanobacteria that is upregulated under low carbon conditions and controlled by the transcription factor NtcA, a central regulator of nitrogen homeostasis. To understand its function, we ectopically overexpressed it in Synechocystis sp. PCC 6803, which resulted in a chlorotic phenotype, delayed growth, severe changes in amino acid pools, and nitrite excretion. Coimmunoprecipitation experiments revealed that this protein targets nitrite reductase, a central enzyme in the assimilation of ammonia from nitrate/nitrite, and was re-named to nitrite reductase regulator protein 1 (NirP1). Our results reveal that NirP1 is widely conserved in cyanobacteria and plays a crucial role in the coordination of C/N primary metabolism by targeting one of the central enzymes. In natural environments, the excreted nitrite will be utilized by other microorganisms; therefore, NirP1 ultimately impacts the activities and composition of the surrounding microbiome.

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Section: Two Transcription Factors Are Involved In the Regulation Of ...supporting

confidence: 91%

Nitrite excretion by cyanobacteria is controlled by the small protein NirP1

Hess,

Kraus,

Spät

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

Protein NirP1 regulates nitrite reductase and nitrite excretion in cyanobacteria

Kraus,

Spät,

Timm

et al. 2024

Nat Commun

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When the supply of inorganic carbon is limiting, photosynthetic cyanobacteria excrete nitrite, a toxic intermediate in the ammonia assimilation pathway from nitrate. It has been hypothesized that the excreted nitrite represents excess nitrogen that cannot be further assimilated due to the missing carbon, but the underlying molecular mechanisms are unclear. Here, we identified a protein that interacts with nitrite reductase, regulates nitrogen metabolism and promotes nitrite excretion. The protein, which we named NirP1, is encoded by an unannotated gene that is upregulated under low carbon conditions and controlled by transcription factor NtcA, a central regulator of nitrogen homeostasis. Ectopic overexpression of nirP1 in Synechocystis sp. PCC 6803 resulted in a chlorotic phenotype, delayed growth, severe changes in amino acid pools, and nitrite excretion. Coimmunoprecipitation experiments indicated that NirP1 interacts with nitrite reductase, a central enzyme in the assimilation of ammonia from nitrate/nitrite. Our results reveal that NirP1 is widely conserved in cyanobacteria and plays a crucial role in the coordination of C/N primary metabolism by targeting nitrite reductase.

show abstract

Nitrite secretion by cyanobacteria is controlled by the small protein NirP1

Kraus,

Spät,

Timm

et al. 2023

Preprint

View full text Add to dashboard Cite

When the supply of inorganic carbon is limiting, photosynthetic cyanobacteria excrete nitrite, a toxic intermediate in the ammonia assimilation pathway from nitrate. While it has been hypothesized that the secreted nitrite represents excess nitrogen that could not be further assimilated due to the missing carbon, the underlying molecular mechanism has remained enigmatic. Here, we characterized a hitherto unannotated gene with homologs in the genomes of 485 different cyanobacteria that is upregulated under low carbon conditions and controlled by the transcription factor NtcA, a central regulator of nitrogen homeostasis. To understand its function, we ectopically overexpressed it in Synechocystis sp. PCC 6803, which resulted in a chlorotic phenotype, delayed growth, severe changes in amino acid pools, and nitrite excretion. Coimmunoprecipitation experiments revealed that this protein targets nitrite reductase, a central enzyme in the assimilation of ammonia from nitrate/nitrite, and was re-named to nitrite reductase regulator protein 1 (NirP1). Our results reveal that NirP1 is widely conserved in cyanobacteria and plays a crucial role in the coordination of C/N primary metabolism by targeting one of the central enzymes. In natural environments, the excreted nitrite will be utilized by other microorganisms; therefore, NirP1 ultimately impacts the activities and composition of the surrounding microbiome.

show abstract

Site-2 Protease Slr1821 Regulates Carbon/Nitrogen Homeostasis during Ammonium Stress Acclimation in Cyanobacterium Synechocystis sp. PCC 6803

Cited by 3 publications

References 75 publications

Nitrite excretion by cyanobacteria is controlled by the small protein NirP1

Nitrite excretion by cyanobacteria is controlled by the small protein NirP1

Protein NirP1 regulates nitrite reductase and nitrite excretion in cyanobacteria

Nitrite secretion by cyanobacteria is controlled by the small protein NirP1

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