The NADP+-isocitrate dehydrogenase gene (icd) is nitrogen regulated in cyanobacteria

Muro‐Pastor, M. Isabel; Reyes, José Carlos Castañeda; Florencio, Francisco J.

doi:10.1128/jb.178.14.4070-4076.1996

Cited by 83 publications

(81 citation statements)

References 58 publications

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“…2-Oxoglutarate synthesis by isocitrate dehydrogenase is the final step of the oxidative branch of the TCA cycle in cyanobacteria (Tandeau de , and its consumption via GOGAT is directly coupled to ammonium assimilation. Consequently, limitation of the GS-GOGAT cycle by ammonium depletion leads to accumulation of 2-oxoglutarate, which serves as an indicator of the cellular nitrogen status (Irmler et al, 1997;Forchhammer, 1999;Muro-Pastor et al, 2001). Two 2-oxoglutarate-responsive elements, P II and NtcA, have been recognized so far in cyanobacteria.…”

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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“…Pyruvate kinase, which is encoded by the pyk gene, catalyzes the conversion of PEP to pyruvate and is one of the key regulatory enzymes in the glycolytic pathway (Knowles et al, 2001). Isocitrate dehydrogenase, encoded by the icd gene, plays an important role in controlling nitrogen and carbon metabolism, because 2OG produced in the isocitrate dehydrogenase reaction is used as a carbon skeleton for nitrogen assimilation in cyanobacteria (Muro-Pastor et al, 1996). Thus, failure to activate these genes has a serious impact on cellular metabolism.…”

Section: Effects Of Addition Of Metabolites On the Dcyabrb2 Mutant Unmentioning

confidence: 99%

Deletion of the Transcriptional Regulator cyAbrB2 Deregulates Primary Carbon Metabolism in Synechocystis sp. PCC 6803

Kaniya¹,

Kizawa²,

Miyagi

et al. 2013

Plant Physiology

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cyAbrB is a transcriptional regulator unique to and highly conserved among cyanobacterial species. A gene-disrupted mutant of cyabrB2 (sll0822) in Synechocystis sp. PCC 6803 exhibited severe growth inhibition and abnormal accumulation of glycogen granules within cells under photomixotrophic conditions. Within 6 h after the shift to photomixotrophic conditions, sodium bicarbonate-dependent oxygen evolution activity markedly declined in the DcyabrB2 mutant, but the decrease in methyl viologen-dependent electron transport activity was much smaller, indicating inhibition in carbon dioxide fixation. Decreases in the transcript levels of several genes related to sugar catabolism, carbon dioxide fixation, and nitrogen metabolism were also observed within 6 h. Metabolome analysis by capillary electrophoresis mass spectrometry revealed that several metabolites accumulated differently in the wild-type and mutant strains. For example, the amounts of pyruvate and 2-oxoglutarate (2OG) were significantly lower in the mutant than in the wild type, irrespective of trophic conditions. The growth rate of the DcyabrB2 mutant was restored to a level comparable to that under photoautotrophic conditions by addition of 2OG to the growth medium under photomixotrophic conditions. Activities of various metabolic processes, including carbon dioxide fixation, respiration, and nitrogen assimilation, seemed to be enhanced by 2OG addition. These observations suggest that cyAbrB2 is essential for the active transcription of genes related to carbon and nitrogen metabolism upon a shift to photomixotrophic conditions. Deletion of cyAbrB2 is likely to deregulate the partition of carbon between storage forms and soluble forms used for biosynthetic purposes. This disorder may cause inactivation of cellular metabolism, excess accumulation of reducing equivalents, and subsequent loss of viability under photomixotrophic conditions.

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“…The roles of PII proteins in regulation of nitrogen metabolism have also been studied in cyanobacteria (18) and Gram-positive bacteria (19)(20)(21), as well as in Archaea (22) and plastids (23). Although glutamine seems to be the primary nitrogen signal (reflecting excess) sensed by PII proteins in enteric bacteria (24), 2OG may be the main signal (reflecting nitrogen deficiency) in some cyanobacteria (25).…”

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confidence: 99%

Regulation of nitrogenase by 2-oxoglutarate-reversible, direct binding of a PII-like nitrogen sensor protein to dinitrogenase

Dodsworth

Leigh

2006

Proc. Natl. Acad. Sci. U.S.A.

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Posttranslational regulation of nitrogenase, or switch-off, in the methanogenic archaeon Methanococcus maripaludis requires both nifI 1 and nifI2, which encode members of the PII family of nitrogenregulatory proteins. Previous work demonstrated that nitrogenase activity in cell extracts was inhibited in the presence of NifI 1 and NifI 2, and that 2-oxoglutarate (2OG), a potential signal of nitrogen limitation, relieved this inhibition. To further explore the role of the NifI proteins in switch-off, we found proteins that interact with NifI 1 and NifI2 and determined whether 2OG affected these interactions. Anaerobic purification of His-tagged NifI 2 resulted in copurification of NifI 1 and the dinitrogenase subunits NifD and NifK, and 2OG or a deletion mutation affecting the T-loop of NifI 2 prevented copurification of dinitrogenase but did not affect copurification of NifI 1. Similar results were obtained with His-tagged NifI 1. Gel-filtration chromatography demonstrated an interaction between purified NifI 1,2 and dinitrogenase that was inhibited by 2OG. The NifI proteins themselves formed a complex of Ϸ85 kDa, which appeared to further oligomerize in the presence of 2OG. NifI 1,2 inhibited activity of purified nitrogenase when present in a 1:1 molar ratio to dinitrogenase, and 2OG fully relieved this inhibition. These results suggest a model for switch-off of nitrogenase activity, where direct interaction of a NifI 1,2 complex with dinitrogenase causes inhibition, which is relieved by 2OG. The presence of nifI 1 and nifI2 in the nif operons of all nitrogenfixing Archaea and some anaerobic Bacteria suggests that this mode of nitrogenase regulation may operate in a wide variety of diazotrophs.ammonia switch-off ͉ Archaea ͉ Methanococcus maripaludis ͉ NifI ͉ posttranslational regulation

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The NADP+-isocitrate dehydrogenase gene (icd) is nitrogen regulated in cyanobacteria

Cited by 83 publications

References 58 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

Deletion of the Transcriptional Regulator cyAbrB2 Deregulates Primary Carbon Metabolism in Synechocystis sp. PCC 6803

Regulation of nitrogenase by 2-oxoglutarate-reversible, direct binding of a PII-like nitrogen sensor protein to dinitrogenase

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