Biosynthesis of Protein Amino Acids in Plant Tissue Culture. III. Studies on the Biosynthesis of Arginine

Dougall, Donald K.; Fulton, Michael M.

doi:10.1104/pp.42.3.387

Cited by 24 publications

(14 citation statements)

References 12 publications

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“…The carbon skeleton of arginine is derived from aketoglutarate via many intermediary steps, with glutamic acid as the first one (8,15). Under the conditions of decreased rate of transamination, it may be assumed that the ["'Ciglutamate was synthesized mainly by activity of glutamic dehydrogenase, PLP nonrequiring enzyme (7), and then instantly used for ornithine synthesis.…”

Section: Discussionmentioning

confidence: 99%

Metabolic Pathway of α-Ketoglutarate in Citrus Leaves as Affected by Phosphorus Nutrition

Achituv¹,

Bar‐Akiva²

1978

Plant Physiol.

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The uptake ad metabolism of a-15-14Clketoglutarate by phospborusdeficient and full nutrient (control) iemo (Citus lmn) leaves were studied over various thme intervals. After 45 minutes In P-deficient leaves, the bulk of Incorporated 14C appeared In organk acids and much less In amino acids, while In the control leaves, the 14C contests of organic and amino acids were equal. In P-efcient leaves, after loger Incubation times the 14C content of organic acids and anino acids Increased, whRe that of CO and residue fractions remaied iow. In full nutrient leaves the "C content of amino acids and organic acids decreased after ionger iocubaton time and Increased in the insolube residue and CO2. In full utient leaves the organic and amino acid metaboUsm were ciosely related and accompanied by protein synthesis and CO2 release, whie in P-deficient leaves an accelerating accumulation of arginine and citric acid was iHnked together With hibitio of protein syntheis and CO liberation.Accumulation of arginine is a well recognized metabolic disturbance induced by phosphorus deficiency in various plants (6,10,11,21). In P-deficient lemon seedlings we found an inverse relationship between their growth and arginine accumulation: as the rate of growth declined the concentration of arginine rose, while the other amino acids and protein remained low in comparison with seedlings grown in full nutrient solution (1). This deviation from the normal pattern of amino acid synthesis may be attributed to a decrease in activity of transaminases, enzymes which require pyridoxal phosphate as a coenzyme (2). In a study of the correlation among phosphate ratio, GOT2 activity, and PLP content, we found that the reduced activity of enzyme could be restored by infiltration of pyridoxal phosphate or mineral phosphate into the P-deficient leaves (2). On the other hand, determinations oforganic acids disclosed extensive accumulation ofcitrate in P-deficient lemon leaves (unpublished data).In the present study we followed the incorporation of a-ketoglutarate into various cell metabolities in P-deficient and normal citrus leaves. In each jar, a small vial containing 1.5 ml of methanol-ethanolamine (4:1, v/v), was placed to trap the "CO2.At the end of the incubation period the radioactivity of CO2 was counted in 10 ml of toluene fluor. During the incubation period, the jars were shaken gently in a water bath at 35 C. The incubation periods were 45, 90, and 180 min. Each combination of treatments (mineral nutrition and incubation period) was tested in three replicates.At the end of the incubation period the buffer solution was filtered through Miracloth. The discs were rinsed with deionized H20, blotted on filter paper, and boiled in 15 ml of 100%o ethanol for 10 min.Extraction. The discs were homogenized for 2 min in a VirTis blender set at speed 60, and centrifuged at 10,000g. The pellet was reextracted four times by shaking for 10 min with 10-ml portions of 80% (v/v) ethanol and then centrifuged (22).The insoluble residue was dried over silica ge...

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Section: Discussionmentioning

confidence: 99%

Metabolic Pathway of α-Ketoglutarate in Citrus Leaves as Affected by Phosphorus Nutrition

Achituv¹,

Bar‐Akiva²

1978

Plant Physiol.

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“…One-gram samples of cells were harvested at selected times and incubated in 25-ml Erlenmeyer flasks containing 5 ml of the medium (pH 7.5). The medium contained 4 ,uCi of NaHW4CO3 (specific radioactivity 10 /Ci/ptmole). The depletion of bicarbonate-"C from the medium was determined by removing 10 ,l of the incubation medium at various time intervals and assaying for radioactivity.…”

Section: Methodsmentioning

confidence: 99%

Contribution of Nonautotrophic Carbon Dioxide Fixation to Protein Synthesis in Suspension Cultures of Paul's Scarlet Rose

Nesius¹,

Fletcher²

1975

Plant Physiol.

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Bicarbonate-'4C was provided to 5-and 11-day-old suspension cultures of Paul's Scarlet rose, and the incorporation of 4C into lipid, protein, amino acids, and organic acids was determined. The rate of bicarbonate uptake was approximately the same by 5-and 11-day-old cells, but the distribution of 4C among cell constituents was markedlv different. In 5-dav-old cells a larger proportion of the "4C entered protein, whereas in 11-day-old cells there was a greater tendency for "4C to accumulate in malate.The '4C in protein was distributed among 10 amino acids each having greater than 1 % of the total 14C recovered in protein. The distribution of "4C among tricarboxylic acid cycle intermediates indicated that the aspartate family of amino acids was synthesized directly from oxaloacetate produced as a result of nonautotrophic C02 fixation. However, this was not the sole source of oxaloacetate used for the synthesis of aspartate, for in a double labeling study with bicarbonate-14C and acetate-3H it was shown that oxaloacetate was drained simultaneously from the tricarboxvlic acid cycle for this purpose.Privation studies have shown that CO2 is required for the normal growth of microbial (22), animal (6, 15), and nonphotosynthetic plant cells (16,19). In explaining this requirement, some authors have emphasized the importance of nonautotrophic CO2 fixation for replenishment of carbon skeletons diverted from the TCA2 cycle into other metabolic pathways (2,16,17,23). Other authors have proposed that the product of CO2 fixation served as a direct source of carbon for amino acid synthesis (7,8,10), and was therefore necessary for growth. In previous work we showed that suspension cultures of Paul's Scarlet rose require CO2 for nonautotrophic growth (13). The present study compared the use of bicarbonate-'4C by 5-versus 11-day-old cells and looked specifically at the relationship of nonautotrophic CO2 fixation to the TCA cycle and the synthesis of amino acids incorporated into protein. growth conditions and composition of the medium were the same as used previously (5, 14), with two exceptions; the concentration of molybdic acid in the medium was 0.01 mg/l, and potassium iodide was 0.5 mg/l. One-gram samples of cells were harvested at selected times and incubated in 25-ml Erlenmeyer flasks containing 5 ml of the medium (pH 7.5). The medium contained 4 ,uCi of NaHW4CO3 (specific radioactivity 10 /Ci/ptmole). The depletion of bicarbonate-"C from the medium was determined by removing 10 ,l of the incubation medium at various time intervals and assaying for radioactivity. The uptake of bicarbonate-4C by cells was corrected for the direct loss of "4CO2 to the atmosphere by running controls which consisted of duplicate amounts of bicarbonate-'4C in a medium containing no cells. MATERIALS AND METHODSAt the end of the incubation period the medium was filtered through Miracloth. The recovered cells were washed thoroughly with deionized water, were placed into 15 ml of hot 80% ethanol, and homogenized for 3 min on a VirTis grind...

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“…The restults in this paper together vith those in the previous parts of this series (5,6,7) indicate that in the actively growing cellis of Patul's Scarlet Rose in tissuie cultture many of the intermediates used in the biosynthesis of the protein aminio acids are the same as those tuseld by other organisms (22). The outstanding exception to this generalization is the pathway of biosynthesis of lysine which in most cells involves diamino-pimelic acid btut in yeasts involves a-amino adipic acid.…”

Section: Discussionmentioning

confidence: 79%

“…Some of the compounds recognized as intermediates in this study have been recognized as intermediates in amino acid biosynthesis in other plants (9). The biosynthesis of arginine was discussed in an earlier paper (7).…”

Section: Discussionmentioning

confidence: 99%

Biosynthesis of Protein Amino Acids in Plant Tissue Culture IV Isotope Competition Experiments using Glucose-U-¹⁴C and Potential Intermediates

Dougall¹,

Fulton²

1967

Plant Physiol.

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Biosynthesis of Protein Amino Acids in Plant Tissue Culture. III. Studies on the Biosynthesis of Arginine

Cited by 24 publications

References 12 publications

Metabolic Pathway of α-Ketoglutarate in Citrus Leaves as Affected by Phosphorus Nutrition

Metabolic Pathway of α-Ketoglutarate in Citrus Leaves as Affected by Phosphorus Nutrition

Contribution of Nonautotrophic Carbon Dioxide Fixation to Protein Synthesis in Suspension Cultures of Paul's Scarlet Rose

Biosynthesis of Protein Amino Acids in Plant Tissue Culture IV Isotope Competition Experiments using Glucose-U-¹⁴C and Potential Intermediates

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Biosynthesis of Protein Amino Acids in Plant Tissue Culture. III. Studies on the Biosynthesis of Arginine

Cited by 24 publications

References 12 publications

Metabolic Pathway of α-Ketoglutarate in Citrus Leaves as Affected by Phosphorus Nutrition

Metabolic Pathway of α-Ketoglutarate in Citrus Leaves as Affected by Phosphorus Nutrition

Contribution of Nonautotrophic Carbon Dioxide Fixation to Protein Synthesis in Suspension Cultures of Paul's Scarlet Rose

Biosynthesis of Protein Amino Acids in Plant Tissue Culture IV Isotope Competition Experiments using Glucose-U-14C and Potential Intermediates

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Biosynthesis of Protein Amino Acids in Plant Tissue Culture IV Isotope Competition Experiments using Glucose-U-¹⁴C and Potential Intermediates