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

Proc Natl Acad Sci U S A. 2004 Aug 17;101(33):12381-6. doi: 10.1073/pnas.0402868101. Epub 2004 Aug 4.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Arabidopsis / drug effects
  • Arabidopsis / genetics
  • Arabidopsis / metabolism
  • Arabidopsis Proteins / chemistry
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Base Sequence
  • Benzamides / pharmacology
  • DNA, Plant / genetics
  • Indoleacetic Acids / pharmacology*
  • Macromolecular Substances
  • Naphthols / pharmacology
  • Naphthoquinones / pharmacology
  • Plants, Genetically Modified
  • Protein Structure, Tertiary
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • SKP Cullin F-Box Protein Ligases / chemistry
  • SKP Cullin F-Box Protein Ligases / genetics
  • SKP Cullin F-Box Protein Ligases / metabolism*


  • Arabidopsis Proteins
  • Benzamides
  • DNA, Plant
  • Indoleacetic Acids
  • Macromolecular Substances
  • Naphthols
  • Naphthoquinones
  • Recombinant Fusion Proteins
  • sirtinol
  • SKP Cullin F-Box Protein Ligases
  • juglone