Auxin-induced SCFTIR1-Aux/IAA interaction involves stable modification of the SCFTIR1 complex.

The plant hormone auxin can regulate gene expression by destabilizing members of the Aux/IAA family of transcriptional repressors. Auxin-induced Aux/IAA degradation requires the protein-ubiquitin ligase SCF(TIR1), with auxin acting to enhance the interaction between the Aux/IAAs and SCF(TIR1). SKP1, Cullin, and an F-box-containing protein (SCF)-mediated degradation is an important component ...
of many eukaryotic signaling pathways. In all known cases to date, the interaction between the targets and their cognate SCFs is regulated by signal-induced modification of the target. The mechanism by which auxin promotes the interaction between SCF(TIR1) and Aux/IAAs is not understood, but current hypotheses propose auxin-induced phosphorylation, hydroxylation, or proline isomerization of the Aux/IAAs. We found no evidence to support these hypotheses or indeed that auxin induces any stable modification of Aux/IAAs to increase their affinity for SCF(TIR1). Instead, we present data suggesting that auxin promotes the SCF(TIR1)-Aux/IAA interaction by affecting the SCF component, TIR1, or proteins tightly associated with it.
Mesh Terms:
Amino Acid Sequence, Arabidopsis, Arabidopsis Proteins, Base Sequence, Benzamides, DNA, Plant, Indoleacetic Acids, Macromolecular Substances, Naphthols, Naphthoquinones, Plants, Genetically Modified, Protein Structure, Tertiary, Recombinant Fusion Proteins, SKP Cullin F-Box Protein Ligases
Proc. Natl. Acad. Sci. U.S.A.
Date: Aug. 17, 2004
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