Abstract
Auxin signaling relies on ubiquitin ligase SCF(TIR1)-mediated 26S proteasome-dependent proteolysis of a large family of short-lived transcription regulators, auxin/indole acetic acid (Aux/IAA), resulting in the derepression of auxin-responsive genes. We have shown previously that a subset of Rac GTPases is activated by auxin, and they in turn stimulate auxin-responsive gene expression. We show here that increasing Rac signaling activity promotes Aux/IAA degradation, whereas downregulating that activity results in the reduction of auxin-accelerated Aux/IAA proteolysis. Observations reported here reveal a novel function for these Rac GTPases as regulators for ubiquitin/26S proteasome-mediated proteolysis and further consolidate their role in auxin signaling. Moreover, our study reveals a cellular process whereby auxin induces and Rac GTPases mediate the recruitment of nucleoplasmic Aux/IAAs into proteolytically active nuclear protein bodies, into which components of the SCF(TIR1), COP9 signalosome, and 26S proteasome are also recruited.
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Claims 4
Claim · model-written summary
Increasing Rac signaling promotes Aux/IAA degradation.
- Taxon
- Tobacco and Arabidopsis
Arabidopsis
Nicotiana tabacumt0 - Treatment
- increasing Rac signaling activitye0
- Gene
- Aux/IAAe0
- Outcome
- Aux/IAA degradatione0
- Direction
- promotese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Tobacco and Arabidopsis”
e0“increasing Rac signaling activity promotes Aux/IAA degradation”
Claim · model-written summary
Downregulating Rac signaling reduces auxin-accelerated Aux/IAA proteolysis.
- Taxon
- Tobacco and ArabidopsisArabidopsisNicotiana tabacumt0
- Treatment
- downregulating that activitye0
- Gene
- Aux/IAAe0
- Outcome
- auxin-accelerated Aux/IAA proteolysise0
- Direction
- reductione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Tobacco and Arabidopsis”
e0“downregulating that activity results in the reduction of auxin-accelerated Aux/IAA proteolysis.”
Claim · model-written summary
Auxin induces Rac-mediated recruitment of Aux/IAAs into proteolytically active nuclear protein bodies.
- Taxon
- Tobacco and ArabidopsisArabidopsisNicotiana tabacumt0
- Treatment
- auxine0
- Gene
- Rac GTPasese0
- Outcome
- recruitment of nucleoplasmic Aux/IAAs into proteolytically active nuclear protein bodiese0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Tobacco and Arabidopsis”
e0“auxin induces and Rac GTPases mediate the recruitment of nucleoplasmic Aux/IAAs into proteolytically active nuclear protein bodies”
Claim · model-written summary
SCF(TIR1), COP9 signalosome and 26S proteasome components are recruited into those nuclear protein bodies.
- Taxon
- Tobacco and ArabidopsisArabidopsisNicotiana tabacumt0
- Outcome
- components of the SCF(TIR1), COP9 signalosome, and 26S proteasome are also recruitede0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Tobacco and Arabidopsis”
e0“components of the SCF(TIR1), COP9 signalosome, and 26S proteasome are also recruited.”
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