Nitrite accumulation by Synechococcus 6301 as a consequence of carbon- or sulfur-deficiency

KRAMER, E

doi:10.1016/0378-1097(89)90484-9

Cited by 5 publications

(6 citation statements)

References 6 publications

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“…The increased 15 N-nitrate in roots implies that NO 3 − reduction and/or its translocation was restricted under S-deficient condition. It has been generally reported that S-limitation results in a reduction of NR activity and an accumulation of amino acids (Reuveny et al 1980, Prosser et al 2001, Nikiforova et al 2006, whereas in cyanobacteria, NR is decreased and nitrite accumulates (Krämer and Schmidt 1989). These data showed that de novo amino acid synthesis derived from newly absorbed N and S decreased by 22.2 and 76.6% at the whole plant level, respectively, during 9 days of S-deficiency (Fig.…”

Section: Discussionmentioning

confidence: 50%

S‐deficiency responsive accumulation of amino acids is mainly due to hydrolysis of the previously synthesized proteins – not to de novo synthesis in Brassica napus

Lee¹,

Muneer

Kim

et al. 2012

Physiologia Plantarum

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To characterize the mechanisms of amino acid accumulation under sulphur (S)-deficiency and its physiological significance in Brassica napus, stable isotopes (15) N and (34) S were employed. The plants were exposed for 9 days to S-deficient conditions (0.05 mM vs 1.5 mM sulphate). After 9 days of S-deficiency, leaf-osmotic potential and total chlorophyll content significantly decreased. S uptake decreased by 94%, whereas N uptake and biomass were not significantly changed. Using (15) N and (34) S labelling, de novo synthesis of amino acids and proteins derived from newly absorbed NO(3) (-) and SO(4) (2) (-) and the content of N and S in the previously synthesized amino acids and proteins were quantified. At the whole plant level, S-deficiency increased the pool of amino acids but resulted in strong decrease of incorporation of newly absorbed NO(3) (-) and SO(4) (2) (-) into amino acids by 22.2 and 76.6%, respectively, compared to the controls. Total amount of N and S incorporated into proteins also decreased by 28.8 and 62.1%, respectively. The levels of (14) N- and (32) S-proteins (previously synthesized proteins) strongly decreased, mainly in mature leaves. The data thus indicate that amino acid accumulation under short-term S-deficiency results from the degradation of previously synthesized proteins rather than from de novo synthesis.

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Section: Discussionmentioning

confidence: 50%

S‐deficiency responsive accumulation of amino acids is mainly due to hydrolysis of the previously synthesized proteins – not to de novo synthesis in Brassica napus

Lee¹,

Muneer

Kim

et al. 2012

Physiologia Plantarum

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“…The decrease of APR activity correlated with decreased mRNA and enzyme levels. On the other hand, in plants, sulfur deficiency results in a reduction of nitrate reductase (NR) activity and an accumulation of amino acids (Reuveny et al, 1980;Migge et al, 2000;Prosser et al, 2001), whereas in cyanobacteria, NR is decreased and nitrite accumulates (Krämer and Schmidt, 1989). However, the reduction of NR activity and mRNA levels seems to be a relatively late process in plant adaptation to sulfur-limiting conditions (Prosser et al, 2001).…”

mentioning

confidence: 99%

Interaction of Sulfate Assimilation with Carbon and Nitrogen Metabolism in Lemna minor

Kopriva

Suter²,

Ballmoos³

et al. 2002

Plant Physiology

114

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Cysteine synthesis from sulfide and O-acetyl-l-serine (OAS) is a reaction interconnecting sulfate, nitrogen, and carbon assimilation. Using Lemna minor, we analyzed the effects of omission of CO 2 from the atmosphere and simultaneous application of alternative carbon sources on adenosine 5Ј-phosphosulfate reductase (APR) and nitrate reductase (NR), the key enzymes of sulfate and nitrate assimilation, respectively. Incubation in air without CO 2 led to severe decrease in APR and NR activities and mRNA levels, but ribulose-1,5-bisphosphate carboxylase/oxygenase was not considerably affected. Simultaneous addition of sucrose (Suc) prevented the reduction in enzyme activities, but not in mRNA levels. OAS, a known regulator of sulfate assimilation, could also attenuate the effect of missing CO 2 on APR, but did not affect NR. When the plants were subjected to normal air after a 24-h pretreatment in air without CO 2 , APR and NR activities and mRNA levels recovered within the next 24 h. The addition of Suc and glucose in air without CO 2 also recovered both enzyme activities, with OAS again influenced only APR. 35 SO 4 2Ϫ feeding showed that treatment in air without CO 2 severely inhibited sulfate uptake and the flux through sulfate assimilation. After a resupply of normal air or the addition of Suc, incorporation of 35 S into proteins and glutathione greatly increased. OAS treatment resulted in high labeling of cysteine; the incorporation of 35 S in proteins and glutathione was much less increased compared with treatment with normal air or Suc. These results corroborate the tight interconnection of sulfate, nitrate, and carbon assimilation.Plants, yeast, and most prokaryotes cover their demand for reduced sulfur, which is essential for function of proteins, oligopeptides, and many coenzymes, by reduction of inorganic sulfate. In the pathway of sulfate assimilation of plants, sulfate is first activated by ATP sulfurylase to adenosine 5Ј-phosphosulfate, which is reduced to sulfite by adenosine 5Ј-phosphosulfate reductase (APR) in a glutathionedependent reaction. Sulfite is further reduced to sulfide by a ferredoxin-dependent sulfite reductase and sulfide incorporated into the amino acid skeleton of O-acetyl-l-Ser (OAS) by OAS (thiol) lyase, forming Cys (Brunold, 1990;Leustek et al., 2000). Cys can further be metabolized to Met or directly incorporated into proteins or glutathione, a tripeptide with important functions as storage and transport form of reduced sulfur, in oxidative stress defense, regulation of sulfur assimilation, etc. (Noctor et al., 1998). Thus, Cys synthesis from OAS and sulfide is a central point of cellular metabolism as this reaction interconnects sulfate, nitrate, and carbon assimilation.Several studies have established regulatory interactions between sulfate and nitrate assimilation in plants (Brunold, 1993;Takahashi and Saito, 1996;Kim et al., 1999;Koprivova et al., 2000). The two assimilatory pathways are well coordinated so that deficiency for one element represses the other pathway. The act...

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“…prior to reducing NO;. Although NO, has been shown to accumulate when Synechococcus 6301 is incubated under conditions of C or S deficiency (Kramer & Schmidt, 1989), it did not accumulate under the conditions we used (5% CO, in the gas stream and 300 pM-MgSO, in the medium). After reducing NO: to NH,+ with Devarda's alloy, the resulting NH,+ was distilled.…”

Section: Methodsmentioning

confidence: 71%

Separating the efflux and influx components of net nitrate uptake by Synechococcus R2 under steady-state conditions

Georgia

Schneider

Kohl

1991

Journal of General Microbiology

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N isotopic discrimination was used to determine the ratio of influx to efflux in experiments in which NO: reduction was decreased (and also net NO; uptake, since under steady-state conditions, net NO? uptake is equal to the rate of reduction) by tungstate. Exponential growth rate constants for the cyanobacterium Synechococcus sp. R2 grown in media containing 0.18 pM-molybdate decreased linearly (0.040 to 0.013 h-l ) with increasing tungstate concentration (0 to 0.2 mM). Values of the overall, observed N isotope effect (Pobs, the ratio of the rate of reaction of 14N-to SN-bearing molecules, normalized to adjust for unequal concentrations) varied inversely and were linear with exponential growth rate. At high tungstate concentration, when the exponential growth rate approached zero (as a result of negligible No: reduction), Pobs approached 1.0197. In the absence of tungstate, Pobs was equal to 1.0037. From this value, we calculated the ratio of efflux to influx to be about 0.19. That is, in the absence of tungstate, more than 80% of the NO: entering the cell underwent reduction with less than 20% released to the medium from the cell. This approach can be used to distinguish changes in influx from changes in metabolic steps in response to factors which affect net uptake rate.

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Nitrite accumulation by Synechococcus 6301 as a consequence of carbon- or sulfur-deficiency

Cited by 5 publications

References 6 publications

S‐deficiency responsive accumulation of amino acids is mainly due to hydrolysis of the previously synthesized proteins – not to de novo synthesis in Brassica napus

S‐deficiency responsive accumulation of amino acids is mainly due to hydrolysis of the previously synthesized proteins – not to de novo synthesis in Brassica napus

Interaction of Sulfate Assimilation with Carbon and Nitrogen Metabolism in Lemna minor

Separating the efflux and influx components of net nitrate uptake by Synechococcus R2 under steady-state conditions

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