2p1o
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(New page: 200px<br /><applet load="2p1o" size="450" color="white" frame="true" align="right" spinBox="true" caption="2p1o, resolution 1.90Å" /> '''Mechanism of Auxin P...)
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Revision as of 11:15, 21 November 2007
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Mechanism of Auxin Perception by the TIR1 ubiquitin ligase
Overview
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.
About this Structure
2P1O is a Protein complex structure of sequences from Arabidopsis thaliana with IHP and NLA as ligands. Full crystallographic information is available from OCA.
Reference
Mechanism of auxin perception by the TIR1 ubiquitin ligase., Tan X, Calderon-Villalobos LI, Sharon M, Zheng C, Robinson CV, Estelle M, Zheng N, Nature. 2007 Apr 5;446(7136):640-5. PMID:17410169
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