Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
. 2002;14 Suppl(Suppl):S81-95.
doi: 10.1105/tpc.010447.

Ubiquitination and auxin signaling: a degrading story

Stefan Kepinski  1 , Ottoline Leyser
Affiliations
Review

Ubiquitination and auxin signaling: a degrading story

Stefan Kepinski et al. Plant Cell. 2002.
No abstract available

PubMed Disclaimer

Figures

Figure 1.
Figure 1.
Auxin Regulates the Ubiquitination of Target Proteins, Marking Them for Degradation by the 26S Proteasome. Key components of this pathway are shown. Target proteins are recruited to the E3 SCF ligase by the F-box protein. Auxin-regulated modification of targets, which include the Aux/IAA proteins, is likely to be required before recognition by the F-box protein. Ubiquitin (Ub) is activated (via an E1 enzyme) and conjugated to the target (via E2–E3 interaction), a process that is reiterated to form a polyubiquitin chain. The ubiquitination activity of the SCF is enhanced by modification of the cullin subunit with the ubiquitin-like protein RUB1. RUB1 is activated by AXR1/ECR1, an E1-like enzyme. The COP9 signalosome regulates the deconjugation of RUB1 (dotted arrow) and possibly other processes relating to the efficient degradation of SCF targets.
Figure 2.
Figure 2.
Protein Structures of Aux/IAAs and ARFs. Aux/IAAs and ARFs share homology in their C-terminal domains III and IV, which mediate homodimerization and heterodimerization. Domain III contains a βαα motif that is important for dimerization. Domain II of Aux/IAAs is required for the auxin-regulated destabilization of the protein. The 13 amino acids that are sufficient to confer instability are shown, and those conserved across the Aux/IAA family are highlighted. ARFs have an N-terminal DNA binding domain (DBD) that binds to TGTCNC-type AuxREs of auxin-regulated genes. The amino acid composition of the middle region (MR) of ARFs affects their ability to activate transcription.
Figure 3.
Figure 3.
Model for Aux/IAA Action. Aux/IAAs form a variety of dimers with both ARFs and other Aux/IAAs. The equilibrium of these dimerization events has the potential to alter gene expression from TGTCNC-containing AuxREs in auxin-responsive promoters. Auxin regulates both the degradation of Aux/IAA proteins and the transcription of Aux/IAA genes. Given that the diverse patterns of degradation and expression with the large Aux/IAA family would lead to considerable temporal variation in the relative abundance of different Aux/IAAs, the interactions are likely to be very complex.
See this image and copyright information in PMC

References

    1. Abel, S., and Theologis, A. (1996). Early genes and auxin action. Plant Physiol. 111 9–17. - PMC - PubMed
    1. Abel, S., Oeller, P.W., and Theologis, A. (1994). Early auxin-induced genes encode short-lived nuclear proteins. Proc. Natl. Acad. Sci. USA 91 326–330. - PMC - PubMed
    1. Abel, S., Nguyen, M.D., and Theologis, A. (1995). The Ps-IAA4/5-like family of early auxin-inducible messenger-RNAs in Arabidopsis thaliana. J. Mol. Biol. 251 533–549. - PubMed
    1. Azevedo, C., Santos-Rosa, M.J., and Shirasu, K. (2001). The U-box protein family in plants. Trends Plant Sci. 6 354–358. - PubMed
    1. Ballas, N., Wong, L.-M., Ke, M., and Theologis, A. (1995). Two auxin-responsive domains interact positively to induce expression of the early indoleacetic acid-inducible gene PS-IAA4/5. Proc. Natl. Acad. Sci. USA 92 3483–3487. - PMC - PubMed

LinkOut - more resources