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.
Department of Biology, University of York, Box 373, York YO10 5YW, United Kingdom.
Stefan
S
Kepinski
Ottoline
O
Leyser
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001549:Benzamides / Q000494:pharmacology; D018744:DNA, Plant / Q000235:genetics; D007210:Indoleacetic Acids / Q000494:pharmacology*; D046911:Macromolecular Substances; D009284:Naphthols / Q000494:pharmacology; D009285:Naphthoquinones / Q000494:pharmacology; D030821:Plants, Genetically Modified; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D044843:SKP Cullin F-Box Protein Ligases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D029681:Arabidopsis Proteins; D001549:Benzamides; D018744:DNA, Plant; D007210:Indoleacetic Acids; D046911:Macromolecular Substances; D009284:Naphthols; D009285:Naphthoquinones; D011993:Recombinant Fusion Proteins; C439060:sirtinol; D044843:SKP Cullin F-Box Protein Ligases; C005134:juglone