Abstract
The enzyme that catalyzes the first step of the shikimate pathway, the 3-deoxy-D-arabino-heptulosonate 7-phosphate (DAHP) synthase (EC 4.1.2.15), was demonstrated in potato (Solanum tuberosum L. cv. Superior) tuber, leaf, root, stem, stolon, in potato cells grown in suspension culture, and in several other plants. The enzyme from potato tuber was purified to electrophoretic homogeneity. The enzyme is a dimeric protein with subunits of 54,000 daltons. The enzyme activity has a narrow pH optimum around pH 7.0. The enzyme is activated by Mn('2+) and tryptophan. The enzyme is hysteretic; tryptophan activation eliminates the hysteresis. Rabbit antibodies were raised against the pure enzyme. The antibodies cross-reacted with DAHP synthase from all parts of the potato plant, as shown by Ouchterlony double diffusion and immunoprecipitation from solution. The antibodies were monospecific as judged by immunodiffusion and immunoelectrophoresis. Antigenic similarities between DAHP synthases from different C(,3) and C(,4) plants were shown by immunoprecipitation from solution. The amount of DAHP synthase polypeptide in various parts of the potato plant was quantitated by rocket immunoelectrophoresis. The largest amount and the highest overall activity of the enzyme was found in the young leaf. Growing stems had the highest specific enzyme activity. The ratios of specific enzyme activity to amount of DAHP synthase polypeptide were not the same for the enzyme from different plant parts or within the potato root during plant development. I interpreted these data to indicate modification of enzyme activity, because I found no evidence for differentially expressed isoenzymes. Subsequently, I demonstrated that the enzyme from Solanum tuberosum cells grown in suspension culture is activated by posttranslational modification, when the cells are challenged with sublethal doses of N-(phosphonomethyl)glycine, the herbicide known as glyphosate which inhibits the penultimate enzyme of the shikimate pathway. In vitro, DAHP synthase from cells of Solanum tuberosum grown in suspension culture is not affected by glyphosate. The in vivo activation of the enzyme demonstrates convincingly that potato DAHP synthase is a regulatory enzyme. Protoplasts, prepared from Solanum tuberosum cells grown in culture, were used for subcellular fractionation of cell organelles. The DAHP synthase was located exclusively in the plastidic fraction of the cell.
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Claims 17
Claim · model-written summary
DAHP synthase was found in potato tuber, leaf, root, stem, stolon and suspension cells.
- Taxon
- potato
Solanum tuberosume0 - Organ / stage
- tuber, leaf, root, stem, stolone0
- Gene
- synthasee0
- Outcome
- was demonstratede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The enzyme that catalyzes the first step of the shikimate pathway, the 3-deoxy-D-arabino-heptulosonate 7-phosphate (DAHP) synthase (EC 4.1.2.15), was demonstrated in potato (Solanum tuberosum L. cv. Superior) tuber, leaf, root, stem, stolon, in potato cells grown in suspension culture”
Claim · model-written summary
Potato tuber DAHP synthase was purified to electrophoretic homogeneity.
- Taxon
- potatoSolanum tuberosume0
- Organ / stage
- tubere0
- Outcome
- purified to electrophoretic homogeneitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The enzyme from potato tuber was purified to electrophoretic homogeneity”
Claim · model-written summary
Potato DAHP synthase is a dimer with 54,000-dalton subunits.
Not reportedTaxon
Verbatim
e0“The enzyme is a dimeric protein with subunits of 54,000 daltons”
t0“POTATO”
Claim · model-written summary
DAHP synthase activity has a pH optimum near 7.0.
Not reportedTaxon
Verbatim
e0“The enzyme activity has a narrow pH optimum around pH 7.0”
t0“POTATO”
Claim · model-written summary
Mn activates potato DAHP synthase.
Not reportedTaxonComparator
Verbatim
e0“The enzyme is activated by Mn('2+) and tryptophan”
t0“POTATO”
Claim · model-written summary
Tryptophan activates potato DAHP synthase.
Not reportedTaxonComparator
Verbatim
e0“The enzyme is activated by Mn('2+) and tryptophan”
t0“POTATO”
Claim · model-written summary
Tryptophan activation eliminates DAHP synthase hysteresis.
Not reportedTaxonComparator
Verbatim
e0“The enzyme is hysteretic; tryptophan activation eliminates the hysteresis”
t0“POTATO”
Claim · model-written summary
Antibodies cross-reacted with DAHP synthase from all potato plant parts.
- Taxon
- potatoSolanum tuberosume0
- Gene
- DAHP synthasee0
- Outcome
- antibodies cross-reactede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The antibodies cross-reacted with DAHP synthase from all parts of the potato plant”
Claim · model-written summary
The antibodies were monospecific.
- Outcome
- antibodies were monospecifice0
Not reportedTaxon
Verbatim
e0“The antibodies were monospecific as judged by immunodiffusion and immunoelectrophoresis”
t0“POTATO”
Claim · model-written summary
DAHP synthases from C(,3) and C(,4) plants shared antigenic similarities.
- Taxon
- plantsViridiplantaee0
- Gene
- DAHP synthasese0
- Outcome
- Antigenic similaritiese0
Verbatim
e0“Antigenic similarities between DAHP synthases from different C(,3) and C(,4) plants were shown”
Claim · model-written summary
Young potato leaves had the largest DAHP synthase amount and highest overall activity.
Not reportedTaxon
Verbatim
e0“The largest amount and the highest overall activity of the enzyme was found in the young leaf”
t0“POTATO”
Claim · model-written summary
Growing stems had the highest specific DAHP synthase activity.
Not reportedTaxon
Verbatim
e0“Growing stems had the highest specific enzyme activity”
t0“POTATO”
Claim · model-written summary
The specific activity to polypeptide ratio varied among plant parts and during root development.
- Taxon
- potatoSolanum tuberosume0
- Organ / stage
- roote0
- Outcome
- ratios of specific enzyme activity to amount of DAHP synthase polypeptidee0
- Direction
- not the samee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The ratios of specific enzyme activity to amount of DAHP synthase polypeptide were not the same for the enzyme from different plant parts or within the potato root during plant development”
Claim · model-written summary
The author interpreted variable ratios as modification of enzyme activity.
- Outcome
- modification of enzyme activitye0
- Qualifier
- no evidence for differentially expressed isoenzymese0
Not reportedTaxon
Verbatim
e0“I interpreted these data to indicate modification of enzyme activity, because I found no evidence for differentially expressed isoenzymes”
t0“POTATO”
Claim · model-written summary
Sublethal glyphosate challenge activated DAHP synthase by posttranslational modification in potato suspension cells.
- Taxon
- Solanum tuberosumSolanum tuberosume0
- Organ / stage
- cells grown in suspension culturee0
- Treatment
- sublethal doses of N-(phosphonomethyl)glycinee0
- Outcome
- enzymee0
- Direction
- activatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the enzyme from Solanum tuberosum cells grown in suspension culture is activated by posttranslational modification, when the cells are challenged with sublethal doses of N-(phosphonomethyl)glycine”
Claim · model-written summary
Glyphosate did not affect DAHP synthase in vitro.
- Taxon
- Solanum tuberosumSolanum tuberosume0
- Treatment
- glyphosatee0
- Outcome
- DAHP synthasee0
- Direction
- not affectede0
- Setting
- In vitroe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In vitro, DAHP synthase from cells of Solanum tuberosum grown in suspension culture is not affected by glyphosate”
Claim · model-written summary
DAHP synthase was exclusively in the plastidic cell fraction.
Not reportedTaxon
Verbatim
e0“The DAHP synthase was located exclusively in the plastidic fraction of the cell”
t0“POTATO”
The same questions in other papers
glyphosate · molecular: metabolites · Solanum tuberosum (potato)Results agree
2 papers in the same direction as this paper
- negative
- no effect
Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.