Carbon supply and 2-oxoglutarate effects on expression of nitrate reductase and nitrogen-regulated genes in<i>Synechococcus</i>sp. strain PCC 7942

Vázquez-Bermúdez, Marı́a Félix; Herrero, Antonia; Flores, Enrique

doi:10.1016/s0378-1097(03)00208-8

Cited by 42 publications

(41 citation statements)

References 35 publications

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“…Consistent with these in vitro properties, the in vivo activity of NtcA is subject to metabolic regulation, such that under conditions of nitrogen excess (low 2-oxoglutarate levels), the NtcA protein is inactive (Luque et al, 2004) even if the ntcA gene is highly expressed from a strong promoter. Increased 2-oxoglutarate concentrations and the absence of ammonium lead to in vivo stimulation of NtcA activity (Vazquez-Bermudez et al, 2003). The ntcA gene is autoregulated by NtcA: the greater the activity of NtcA, the more NtcA protein is produced, resulting in a strong increase of NtcA abundance under nitrogen-limited conditions (Luque et al, 2004).…”

Section: Acclimation To Nitrogen Deprivationmentioning

confidence: 99%

Acclimation of unicellular cyanobacteria to macronutrient deficiency: emergence of a complex network of cellular responses

2005

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Cyanobacteria are equipped with numerous mechanisms that allow them to survive under conditions of nutrient starvation, some of which are unique to these organisms. This review surveys the molecular mechanisms underlying acclimation responses to nitrogen and phosphorus deprivation, with an emphasis on non-diazotrophic freshwater cyanobacteria. As documented for other micro-organisms, nutrient limitation of cyanobacteria elicits both general and specific responses. The general responses occur under any starvation condition and are the result of the stresses imposed by arrested anabolism. In contrast, the specific responses are acclimation processes that occur as a result of limitation for a particular nutrient; they lead to modification of metabolic and physiological routes to compensate for the restriction. First, the general acclimation processes are discussed, with an emphasis on modifications of the photosynthetic apparatus. The molecular mechanisms underlying specific responses to phosphorus and nitrogen-limitation are then outlined, and finally the cross-talk between pathways modulating specific and general responses is described.

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Section: Acclimation To Nitrogen Deprivationmentioning

confidence: 99%

Acclimation of unicellular cyanobacteria to macronutrient deficiency: emergence of a complex network of cellular responses

2005

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“…The observed repression of PnirA-dependent gene expression at 10 µM ammonium was consistent with other reports demonstrating repression in cyanobacteria at similar ammonium concentrations (Flores et al 1980;Dortch 1990). In addition to photosynthetically derived reducing power needed to reduce nitrate to ammonium during assimilation, more recent studies have shown that NtcA-dependent activation of nitrogen assimilatory genes requires α-ketoglutarate as a coinducer (Tanigawa et al 2002;Vasquez-Bermudez et al 2003). Taking this into account, photosynthetic light reactions and carbon fixation together likely influence the activation of transcription during nitrogen limitation.…”

Section: Assessmentmentioning

confidence: 99%

Construction and characterization of a cyanobacterial bioreporter capable of assessing nitrate assimilatory capacity in freshwaters

Ivanikova

McKay

Bullerjahn

2005

Limnol. Oceanogr. Methods

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The use of cyanobacterial whole-cell luminescent bioreporters has enhanced our ability to monitor nutrient availability in aquatic ecosystems. We have constructed a Synechocystis sp. strain PCC6803 bioluminescent reporter for the assessment of nitrate bioavailability. Specifically, a 380-base pair DNA fragment containing the NtcA/B-dependent nitrate/nitrite-activated nirA promoter (regulating expression of genes encoding nitrite reductase) was fused to the bacterial luciferase genes, luxAB, and introduced into Synechocystis by genetic transformation. Characterization of this strain, designated AND100, yielded dose-dependent increased bioluminescence coincident with increased nitrate added to the growth medium from 1 to 100 µM. Bioluminescence in response to nitrate addition was light dependent up to 50 µmol quanta m -2 s -1

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“…PCC 7942 (Forchhammer & Hedler, 1997). It was also found that changes in the intracellular pool of 2-oxoglutarate correlated to the expression of genes dependent on NtcA, a global nitrogen control protein highly conserved among cyanobacteria Vazquez-Bermudez et al, 2003). 2-Oxoglutarate was therefore proposed as a signal reflecting the nitrogen status within cells (MuroPastor et al, 2001).…”

Section: Discussionmentioning

confidence: 99%

“…Consistent with this idea, 2-oxoglutarate stimulates the expression of the activity of nitrate (NO { 3 ) reductase and the transcription of two nitrogen-regulated genes, nir and amt1, in Synechococcus sp. PCC 7942 (Vazquez-Bermudez et al, 2003). Two cyanobacterial proteins are known to interact with 2-oxoglutarate, NtcA (for a review, see Herrero et al, 2001) and PII (Forchhammer & Hedler, 1997).…”

Section: Introductionmentioning

confidence: 99%

An increase in the level of 2-oxoglutarate promotes heterocyst development in the cyanobacterium Anabaena sp. strain PCC 7120

Laurent

Konde

et al. 2003

Microbiology

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In the filamentous cyanobacterium Anabaena sp. strain PCC 7120, a starvation of combined nitrogen induces differentiation of heterocysts, cells specialized in nitrogen fixation. How do filaments perceive the limitation of the source of combined nitrogen, and what determines the proportion of heterocysts? In cyanobacteria, 2-oxoglutarate provides a carbon skeleton for the incorporation of inorganic nitrogen. Recently, it has been proposed that the concentration of 2-oxoglutarate reflects the nitrogen status in cyanobacteria. To investigate the effect of 2-oxoglutarate on heterocyst development, a heterologous gene encoding a 2-oxoglutarate permease under the control of a regulated promoter was expressed in Anabaena sp. PCC 7120. The increase of 2-oxoglutarate within cells can trigger heterocyst differentiation in a subpopulation of filaments even in the presence of nitrate. In the absence of a source of combined nitrogen, it can increase heterocyst frequency, advance the timing of commitment to heterocyst development and further increase the proportion of heterocysts in a patS mutant. Here, it is proposed that the intracellular concentration of 2-oxoglutarate is involved in the determination of the proportion of the two cell types according to the carbon/nitrogen status of the filament.

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Carbon supply and 2-oxoglutarate effects on expression of nitrate reductase and nitrogen-regulated genes inSynechococcussp. strain PCC 7942

Cited by 42 publications

References 35 publications

Acclimation of unicellular cyanobacteria to macronutrient deficiency: emergence of a complex network of cellular responses

Acclimation of unicellular cyanobacteria to macronutrient deficiency: emergence of a complex network of cellular responses

Construction and characterization of a cyanobacterial bioreporter capable of assessing nitrate assimilatory capacity in freshwaters

An increase in the level of 2-oxoglutarate promotes heterocyst development in the cyanobacterium Anabaena sp. strain PCC 7120

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