Abstract
Phosphatidic acid (PA) has only recently been identified as an important eukaryotic lipid-signalling molecule. In plants, PA formation is triggered by various biotic and abiotic stresses, including wounding, pathogen attack, drought, salinity, cold, and freezing. However, few molecular targets of PA have been identified so far. One of the best characterized is Raf-1, a mammalian MAPKKK. Arabidopsis thaliana CTR1 (constitutive triple response 1) is one of the plant homologues of Raf-1 and functions as a negative regulator of the ethylene signalling pathway. Here, it is shown that PA binds CTR1 and inhibits its kinase activity. Using different PA-binding assays, the kinase domain of CTR1 (CTR1-K) was found to bind PA directly. Addition of PA resulted in almost complete inhibition of CTR1 kinase activity and disrupted the intramolecular interaction between CTR1-K and the CTR1 N-terminal regulatory domain. Additionally, PA blocked the interaction of CTR1 with ETR1, one of the ethylene receptors. The basic amino acid motif shown to be required for PA binding in Raf-1 is conserved in CTR1-K. However, mutations in this motif did not affect either PA-binding or PA-dependent inhibition of CTR1 activity. Subsequent deletion analysis of CTR1's kinase domain revealed a novel PA-binding region at the C-terminus of the kinase.
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Claims 6
Claim · model-written summary
Addition of PA almost completely inhibited CTR1 kinase activity.
- Taxon
- Arabidopsis thaliana
Arabidopsis thalianae0 - Treatment
- Addition of PAe1
- Gene
- CTR1e1
- Outcome
- CTR1 kinase activitye1
- Direction
- almost complete inhibitione1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Arabidopsis thaliana CTR1”
e1“Addition of PA resulted in almost complete inhibition of CTR1 kinase activity and disrupted the intramolecular interaction between CTR1-K and the CTR1 N-terminal regulatory domain”
Claim · model-written summary
The kinase domain of CTR1 (CTR1-K) binds PA directly.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae0
- Gene
- CTR1-Ke2
- Outcome
- bind PA directlye2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Arabidopsis thaliana CTR1”
e2“Using different PA-binding assays, the kinase domain of CTR1 (CTR1-K) was found to bind PA directly”
Claim · model-written summary
PA disrupted the intramolecular interaction between CTR1-K and the CTR1 N-terminal regulatory domain.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae0
- Treatment
- Addition of PAe1
- Gene
- CTR1-Ke1
- Outcome
- intramolecular interaction between CTR1-K and the CTR1 N-terminal regulatory domaine1
- Direction
- disruptede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Arabidopsis thaliana CTR1”
e1“Addition of PA resulted in almost complete inhibition of CTR1 kinase activity and disrupted the intramolecular interaction between CTR1-K and the CTR1 N-terminal regulatory domain”
Claim · model-written summary
PA blocked the interaction of CTR1 with ETR1.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae0
- Treatment
- PAe3
- Gene
- ETR1e3
- Outcome
- interaction of CTR1 with ETR1e3
- Direction
- blockede3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Arabidopsis thaliana CTR1”
e3“PA blocked the interaction of CTR1 with ETR1, one of the ethylene receptors”
Claim · model-written summary
Mutations in the basic motif did not affect PA-binding or PA-dependent inhibition of CTR1 activity.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae0
- Treatment
- mutations in this motife4
- Gene
- CTR1e4
- Outcome
- PA-binding or PA-dependent inhibition of CTR1 activitye4
- Direction
- did not affecte4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Arabidopsis thaliana CTR1”
e4“mutations in this motif did not affect either PA-binding or PA-dependent inhibition of CTR1 activity”
Claim · model-written summary
A novel PA-binding region lies at the C-terminus of the CTR1 kinase.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae0
- Outcome
- PA-binding regione5
- Qualifier
- at the C-terminus of the kinasee5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Arabidopsis thaliana CTR1”
e5“a novel PA-binding region at the C-terminus of the kinase”
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