2P1Q

Mechanism of Auxin Perception by the TIR1 ubiquitin ligase

Summary for 2P1Q

• Entry DOI: 10.2210/pdb2p1q/pdb
• Related: 2P1M 2P1N 2P1O 2P1P
• Descriptor: SKP1-like protein 1A, TRANSPORT INHIBITOR RESPONSE 1 protein, Auxin-responsive protein IAA7, ... (6 entities in total)
• Functional Keywords: f-box, leucine rich repeat, signaling protein
• Biological source: Arabidopsis thaliana (thale cress); More
• Total number of polymer chains: 3
• Total formula weight: 87188.57

Authors

Tan, X.,Calderon-Villalobos, L.I.A.,Sharon, M.,Robinson, C.V.,Estelle, M.,Zheng, N. (deposition date: 2007-03-06, release date: 2007-04-10, Last modification date: 2023-08-30)

Primary citation

Tan, X.,Calderon-Villalobos, L.I.,Sharon, M.,Zheng, C.,Robinson, C.V.,Estelle, M.,Zheng, N.
Mechanism of auxin perception by the TIR1 ubiquitin ligase.
Nature, 446:640-645, 2007

PubMed Abstract: Auxin is a pivotal plant hormone that controls many aspects of plant growth and development. Perceived by a small family of F-box proteins including transport inhibitor response 1 (TIR1), auxin regulates gene expression by promoting SCF ubiquitin-ligase-catalysed degradation of the Aux/IAA transcription repressors, but how the TIR1 F-box protein senses and becomes activated by auxin remains unclear. Here we present the crystal structures of the Arabidopsis TIR1-ASK1 complex, free and in complexes with three different auxin compounds and an Aux/IAA substrate peptide. These structures show that the leucine-rich repeat domain of TIR1 contains an unexpected inositol hexakisphosphate co-factor and recognizes auxin and the Aux/IAA polypeptide substrate through a single surface pocket. Anchored to the base of the TIR1 pocket, auxin binds to a partially promiscuous site, which can also accommodate various auxin analogues. Docked on top of auxin, the Aux/IAA substrate peptide occupies the rest of the TIR1 pocket and completely encloses the hormone-binding site. By filling in a hydrophobic cavity at the protein interface, auxin enhances the TIR1-substrate interactions by acting as a 'molecular glue'. Our results establish the first structural model of a plant hormone receptor.

PubMed: 17410169
DOI: 10.1038/nature05731

Experimental method

X-RAY DIFFRACTION (1.91 Å)