Abstract
The acquisition of nutrients requires tight regulation to ensure optimal supply while preventing accumulation to toxic levels. Ammonium transporter/methylamine permease/rhesus (AMT/Mep/Rh) transporters are responsible for ammonium acquisition in bacteria, fungi, and plants. The ammonium transporter AMT1;1 from Arabidopsis thaliana uses a novel regulatory mechanism requiring the productive interaction between a trimer of subunits for function. Allosteric regulation is mediated by a cytosolic C-terminal trans-activation domain, which carries a conserved Thr (T460) in a critical position in the hinge region of the C terminus. When expressed in yeast, mutation of T460 leads to inactivation of the trimeric complex. This study shows that phosphorylation of T460 is triggered by ammonium in a time- and concentration-dependent manner. Neither Gln nor l-methionine sulfoximine-induced ammonium accumulation were effective in inducing phosphorylation, suggesting that roots use either the ammonium transporter itself or another extracellular sensor to measure ammonium concentrations in the rhizosphere. Phosphorylation of T460 in response to an increase in external ammonium correlates with inhibition of ammonium uptake into Arabidopsis roots. Thus, phosphorylation appears to function in a feedback loop restricting ammonium uptake. This novel autoregulatory mechanism is capable of tuning uptake capacity over a wide range of supply levels using an extracellular sensory system, potentially mediated by a transceptor (i.e., transporter and receptor).
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 6
Claim · model-written summary
Mutation of T460 inactivates the trimeric AMT1;1 complex in yeast.
- Taxon
- Arabidopsis thaliana
Arabidopsis thalianae1 - Treatment
- mutation of T460e0
- Gene
- T460e0
- Outcome
- inactivation of the trimeric complexe0
- Setting
- yeaste0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When expressed in yeast, mutation of T460 leads to inactivation of the trimeric complex.”
e1“AMT1;1 from Arabidopsis thaliana uses”
t1“When expressed in yeast, mutation of T460 leads to inactivation of the trimeric complex.”
Claim · model-written summary
Ammonium triggers T460 phosphorylation according to time and concentration.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Gene
- T460e0
- Compound
- ammoniume0
- Outcome
- phosphorylation of T460e0
- Qualifier
- time- and concentration-dependent mannere0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“phosphorylation of T460 is triggered by ammonium in a time- and concentration-dependent manner.”
e1“AMT1;1 from Arabidopsis thaliana uses”
t1“When expressed in yeast, mutation of T460 leads to inactivation of the trimeric complex.”
Claim · model-written summary
Gln did not induce T460 phosphorylation.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Treatment
- Glne0
- Outcome
- phosphorylatione0
- Direction
- Neithere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Neither Gln nor l-methionine sulfoximine-induced ammonium accumulation were effective in inducing phosphorylation”
e1“AMT1;1 from Arabidopsis thaliana uses”
t1“When expressed in yeast, mutation of T460 leads to inactivation of the trimeric complex.”
Claim · model-written summary
l-methionine sulfoximine-induced ammonium accumulation did not induce phosphorylation.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Treatment
- l-methionine sulfoximine-induced ammonium accumulatione0
- Outcome
- phosphorylatione0
- Direction
- Neithere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Neither Gln nor l-methionine sulfoximine-induced ammonium accumulation were effective in inducing phosphorylation”
e1“AMT1;1 from Arabidopsis thaliana uses”
t1“When expressed in yeast, mutation of T460 leads to inactivation of the trimeric complex.”
Claim · model-written summary
External ammonium-induced T460 phosphorylation correlates with inhibited root ammonium uptake.
- Taxon
- ArabidopsisArabidopsise0
- Organ / stage
- rootse0
- Gene
- T460e0
- Compound
- external ammoniume0
- Outcome
- ammonium uptake into Arabidopsis rootse0
- Direction
- inhibitione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Phosphorylation of T460 in response to an increase in external ammonium correlates with inhibition of ammonium uptake into Arabidopsis roots.”
Claim · model-written summary
T460 phosphorylation appears to restrict ammonium uptake through feedback.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Gene
- T460t1
- Outcome
- ammonium uptakee0
- Qualifier
- feedback loop restrictinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“phosphorylation appears to function in a feedback loop restricting ammonium uptake.”
e1“AMT1;1 from Arabidopsis thaliana uses”
t1“When expressed in yeast, mutation of T460 leads to inactivation of the trimeric complex.”
The same questions in other papers
L-methionine · molecular: expression · Arabidopsis thaliana (thale cress)Results agree
1 paper in the same direction as this paper
- negative
nitrogen · molecular: expression · Arabidopsis thaliana (thale cress)Positive and negative results
7 papers in the same direction as this paper · 6 in the opposite direction
- positive
- positive
- positive
10 papers more in this group
See all 14 papers →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.