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Proc Natl Acad Sci U S A. 2004 Aug 17;101(33):12381-6. Epub 2004 Aug 4.

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

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  • 1Department of Biology, University of York, Box 373, York YO10 5YW, United Kingdom.

Abstract

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.

PMID:
15295098
[PubMed - indexed for MEDLINE]
PMCID:
PMC514484
Free PMC Article
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