Editor's Summary
5 April 2007
Auxin action revealed
The mechanism by which the plant hormone auxin regulates plant growth has puzzled scientists since Darwin's time. Auxin is known to regulate gene expression by binding to its receptor TIR1 and promoting ubiquitin-dependent degradation of Aux/IAA repressor proteins. Now the determination of the crystal structures of TIR1 in complexes with three different auxins and an Aux/IAA peptide shows auxin to act as a 'molecular glue' promoting interactions between the receptor and proteins targeted for degradation. As well as revealing auxin's mechanism, this work establishes the first structural model of a plant hormone receptor. Also, the discovery that a small molecule like auxin can regulate ubiquitin ligases suggests a novel strategy for developing therapeutics for human disorders associated with ubiquitin ligase defects. On the cover, auxin (shown as a spacefilling model) is seen in the cavity between TIR1 (blue) and IAA7 peptide (orange).
News and Views: Plant biology: Sticking with auxin
Auxin is one of the main agents that regulate plant growth and development. Intricate crystallographic studies reveal how this hormone acts as a 'molecular glue' in mediating substrate–receptor interactions.
Tom Guilfoyle
doi:10.1038/446621a
Article: Mechanism of auxin perception by the TIR1 ubiquitin ligase
Xu Tan, Luz Irina A. Calderon-Villalobos, Michal Sharon, Changxue Zheng, Carol V. Robinson, Mark Estelle & Ning Zheng
doi:10.1038/nature05731
Abstract | Full Text | PDF (1,079K) | Supplementary information
