The role of regulated protein degradation in auxin response

@article{Dharmasiri2004TheRO,
  title={The role of regulated protein degradation in auxin response},
  author={Sunethra Dharmasiri and Mark Estelle},
  journal={Plant Molecular Biology},
  year={2004},
  volume={49},
  pages={401-408}
}
Auxin-regulated gene expression is mediated by two families of transcription factors. The ARF proteins bind to a conserved DNA sequence called the AuxRE and activate transcription. The Aux/IAA proteins repress ARF function, presumably by forming dimers with ARF proteins. Recent genetic studies in Arabidopsis indicate that auxin regulates this system by promoting the ubiquitin-mediated degradation of the Aux/IAA proteins, thus permitting ARF function. Mutations in components of SCFTIR1, a… 

Auxin signaling and regulated protein degradation.

Auxin-responsive gene expression: genes, promoters and regulatory factors

TLDR
A molecular approach to investigate auxin signaling in plants has led to the identification of several classes of early/primary auxin response genes, and a family of trans-acting transcription factors that bind with specificity to AuxREs has been characterized.

The IAA 1 protein is encoded by AXR 5 and is a substrate of SCFTIR 1

TLDR
The results provide further support for a model in which most members of the Aux/IAA family are targeted for degradation by SCF in response to auxin, and show that IAA1/AXR5 interacts with TIR1 in an auxin-dependent manner.

The IAA1 protein is encoded by AXR5 and is a substrate of SCF(TIR1).

TLDR
The results provide further support for a model in which most members of the Aux/IAA family are targeted for degradation by SCFTIR1 in response to auxin, and show that the mutant phenotype is caused by the accumulation of IAA1/AXR5.

Genetics of Aux/IAA and ARF action in plant growth and development

TLDR
A review of mutations that affect auxin-modulated transcription factors, in particular those in the Aux/IAA and AUXIN RESPONSE FACTOR(ARF) genes, and potential mechanisms for interactions between auxin and light response pathways suggested by these mutants.

Protein phosphorylation in the delivery of and response to auxin signals

TLDR
Recent studies that suggest roles for protein phosphorylation in regulation of both auxin responses and polar auxin transport and in regulating the activity or turnover of auxin-responsive transcription factors are discussed.

The ubiquitin-proteasome system regulates plant hormone signaling.

TLDR
This work has shown that E3 ubiquitin ligases in particular actively participate in hormone perception, de-repression of hormone signaling pathways, degradation of hormone specific transcription factors, and regulation of hormone biosynthesis.

Identification of inhibitors of auxin transcriptional activation by means of chemical genetics in Arabidopsis.

TLDR
A high-throughput screen for identifying small molecule inhibitors of auxin signaling in Arabidopsis revealed several potent lead structures that abrogate transcription of an auxin-inducible reporter gene and mechanistic similarities of the two most potent molecules were demonstrated.

MicroRNA-Directed Regulation of Arabidopsis AUXIN RESPONSE FACTOR17 Is Essential for Proper Development and Modulates Expression of Early Auxin Response Genesw⃞

TLDR
Many of these defects resemble phenotypes previously observed in plants expressing viral suppressors of RNA silencing and plants with mutations in genes important for miRNA biogenesis or function, providing a molecular rationale for Phenotypes previously associated with more general disruptions of miRNA function.

AtCAND1, A HEAT-Repeat Protein That Participates in Auxin Signaling in Arabidopsis1

TLDR
This work describes the isolation, characterization, and cloning of an Arabidopsis mutant Atcand1-1 that emerged from a genetic screen for mutants insensitive to sirtinol, and helps to elucidate the roles of AtCAND1 in protein degradation and auxin signaling.
...

References

SHOWING 1-10 OF 54 REFERENCES

Auxin regulates SCFTIR1-dependent degradation of AUX/IAA proteins

TLDR
It is shown that SCFTIR1 is required for AUX/IAA degradation, and it is proposed that auxin promotes the degradation of this large family of transcriptional regulators, leading to diverse downstream effects.

Changes in auxin response from mutations in an AUX/IAA gene.

TLDR
AXR3 was shown to be a member of the AUX/IAA family, providing direct evidence that AUX/(IAA) genes are central in auxin signaling, and molecular characterization of axr3 gain-of-function and loss- of-function mutations established the functional importance of domains conserved among AUX-IAA proteins.

Identification of an SCF ubiquitin-ligase complex required for auxin response in Arabidopsis thaliana.

TLDR
In Arabidopsis, auxin response is dependent on a ubiquitin-ligase (E3) complex called SCFTIR1, which provides new support for a model in which auxin action depends on the regulated proteolysis of repressor proteins.

Genetics of Aux/IAA and ARF action in plant growth and development

TLDR
A review of mutations that affect auxin-modulated transcription factors, in particular those in the Aux/IAA and AUXIN RESPONSE FACTOR(ARF) genes, and potential mechanisms for interactions between auxin and light response pathways suggested by these mutants.

Activation and repression of transcription by auxin-response factors.

TLDR
The results suggest that ARFs can activate or repress transcription by binding to AuxREs directly and that selected ARFs, when overexpressed, may potentiate activation further by associating with an endogenous transcription factor(s) (e.g., an ARF) that is bound to auxREs.

The ubiquitin-related protein RUB1 and auxin response in Arabidopsis.

The AXR1 (auxin-resistant) protein, which has features of the ubiquitin-activating enzyme E1, is required for normal response to the plant hormone auxin in Arabidopsis thaliana. ECR1 functions

Degradation of Aux/IAA proteins is essential for normal auxin signalling.

TLDR
It is suggested that rapid degradation of Aux/IAA proteins is necessary for a normal auxin response, and transgenic plants engineered to over-express IAA17 have an axr3-like phenotype.

Early auxin-induced genes encode short-lived nuclear proteins.

TLDR
It is suggested that plant tissues express short-lived nuclear proteins as a primary response to IAA and these proteins act as activators or repressors of genes responsible for mediating the various auxin responses.

The TIR1 protein of Arabidopsis functions in auxin response and is related to human SKP2 and yeast grr1p.

TLDR
The identification of a new gene called TRANSPORT InhIBITor RESPONSE 1 (TIR1), which contains a series of leucine-rich repeats and a recently identified motif called an F box, indicates that TIR1 is also required for normal response to auxin.

Aux/IAA proteins repress expression of reporter genes containing natural and highly active synthetic auxin response elements.

TLDR
Cotransfection experiments with natural and synthetic AuxRE reporter genes and effector genes encoding Aux/IAA proteins showed that overexpression of Aux/ IAA proteins in carrot protoplasts resulted in specific repression of TGTCTC Auxre reporter gene expression.
...