Abstract
Acidification of soils may release water soluble, toxic aluminium species from clay minerals. Al interferes with a wide range of physical and cellular processes. Glutamine synthetase (GS, EC 6.3.1.2) is the key enzyme of primary N assimilation, as well as ammonia reassimilation and detoxification. Plant GS requires two magnesium ions per subunit for activity, which makes GS a potential target of metal stress. The objective of this investigation was to prove that Al from an organic metal complex is able to activate GS, and Al becomes bound to the polypeptide structure of the GS molecule. Aluminium(III)-nitrilotriacetic acid complex (Al(III)NTA) activated the GS prepared from wheat (Triticum aestivum L.) leaves, as Al(3+) did in vivo, but could not functionally substitute magnesium ions, which were also necessary for the activity in the in vitro GS assay. GS2 was isolated by non-denaturing polyacrylamide gel electrophoresis, and the Al and Mg content of the enzyme was determined by inductively coupled plasma atomic emission spectroscopy. The GS octamer remained intact and contained Mg(2+) bound to its specific sites after the electrophoretic separation. Al was detected in the Al(III)NTA-treated sample bound to the structure of the enzyme protein, potentially occupying one of the specific metal-binding sites of the subunits. Our results indicate that the activatory effect of the Al(III)NTA complex is because of specific binding of aluminium to the polypeptide chain of GS2, however presence of magnesium at least on one of the metal-binding sites is essential to the active state of the enzyme.
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Claims 7
Claim · model-written summary
Al(III)NTA activated GS from wheat leaves, as Al(3+) did in vivo.
- Taxon
- wheat
Triticum aestivume0 - Treatment
- Aluminium(III)-nitrilotriacetic acid complex (Al(III)NTA)e0
- Gene
- GSe0
- Outcome
- GSe0
- Direction
- activatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Aluminium(III)-nitrilotriacetic acid complex (Al(III)NTA) activated the GS prepared from wheat (Triticum aestivum L.) leaves, as Al(3+) did in vivo”
Claim · model-written summary
Al(III)NTA could not substitute functionally for magnesium ions in the GS assay.
- Taxon
- wheatTriticum aestivume1
- Gene
- GSe0
- Outcome
- activity in the in vitro GS assaye0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“could not functionally substitute magnesium ions, which were also necessary for the activity in the in vitro GS assay”
e1“GS prepared from wheat (Triticum aestivum L.) leaves”
Claim · model-written summary
The GS octamer remained intact after electrophoresis.
- Taxon
- wheatTriticum aestivume1
- Gene
- GSe0
- Outcome
- GS octamer remained intacte0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The GS octamer remained intact and contained Mg(2+) bound to its specific sites after the electrophoretic separation”
e1“GS prepared from wheat (Triticum aestivum L.) leaves”
Claim · model-written summary
Mg(2+) remained bound to GS sites after electrophoresis.
- Taxon
- wheatTriticum aestivume1
- Gene
- GSe0
- Outcome
- contained Mg(2+) bound to its specific sitese0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The GS octamer remained intact and contained Mg(2+) bound to its specific sites after the electrophoretic separation”
e1“GS prepared from wheat (Triticum aestivum L.) leaves”
Claim · model-written summary
Al was detected bound to the enzyme protein in treated samples.
- Taxon
- wheatTriticum aestivume1
- Treatment
- Al(III)NTA-treatede0
- Outcome
- Al was detectede0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Al was detected in the Al(III)NTA-treated sample bound to the structure of the enzyme protein”
e1“GS prepared from wheat (Triticum aestivum L.) leaves”
Claim · model-written summary
The authors attribute GS2 activation to aluminium binding to the polypeptide chain.
- Taxon
- wheatTriticum aestivume1
- Gene
- GS2e0
- Compound
- aluminiume0
- Outcome
- activatory effecte0
- Qualifier
- specific binding of aluminium to the polypeptide chaine0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the activatory effect of the Al(III)NTA complex is because of specific binding of aluminium to the polypeptide chain of GS2”
e1“GS prepared from wheat (Triticum aestivum L.) leaves”
Claim · model-written summary
Magnesium at one or more metal binding sites was considered essential for enzyme activity.
- Taxon
- wheatTriticum aestivume1
- Compound
- magnesiume0
- Outcome
- active state of the enzymee0
- Qualifier
- at least on one of the metal-binding sitese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“presence of magnesium at least on one of the metal-binding sites is essential to the active state of the enzyme”
e1“GS prepared from wheat (Triticum aestivum L.) leaves”
The same questions in other papers
aluminium atom · physiology: gas exchange · Triticum aestivum (wheat)Positive and negative results
1 paper in the same direction as this paper · 1 in the opposite direction
- negative
- positive
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.